It's no stretch to say that ads are what make the Web go 'round. The content you're reading right now? Paid for by ads. Google, Facebook, Pandora, YouTube? Driven by ads. This is not a new concept: TV and radio have relied on commercials since their earliest days. Because, let's face it, something has to pay for all the free programming and services.Of course, there are ways that users can quell the seemingly endless stream of buttons, banners, video interstitials and more. All you need is an ad blocker: a browser plug-in designed to filter out those unwanted distractions and interruptions.For many users, though, there's another concern that is more important than simple annoyance: privacy. Some sites do more than just plaster their content with digital billboards. They log your visits (usually via IP addresses) and even track your movements to other destinations. Although the driving motivator is usually just broad-based data-gathering, it can be unsettling to realize you're being followed online.In response, some plug-ins go beyond mere filtering, promising full-on privacy protection against cookies, trackers, third-party scripts and widgets, and other unwanted invasions.In this roundup I chose six products: AdBlock, Adblock Plus, Disconnect, DoNotTrackMe, Ghostery and Privacy Badger. There are dozens of other, similar, tools, but these represent a good cross-section of what's available. They're also among the most popular picks in the Chrome and Firefox extensions libraries.While a few of these plug-ins have companion apps designed to extend protection to mobile devices, for purposes of this roundup I focused on desktop browsers. I concentrated on two browsers, Internet Explorer and Google Chrome, which have a combined market share of nearly 80%, according to Netmarketshare.I installed one plug-in at a time, then visited a wide range of sites -- including, but not limited to, Crackle, Facebook, Giveaway of the Day, Huffington Post, Hulu, TMZ, Tucows Downloads and YouTube. These sites represent both mainstream and lesser-known destinations -- some notoriously ad-heavy, others focused expressly on video or downloads. Certainly different sites will be affected differently by different ad-blockers, but overall I got a good picture of what day-to-day browsing looks like with each one.I looked at these sites with each plug-in toggled on, then again with it toggled off. The idea was to make sure none of them were overzealous in filtering, messing with either the content or page layout.What about speed? In theory, ad blockers and privacy filters should make pages appear faster, as they cut down the amount of content that needs to load. However, this can be difficult to gauge in real-world testing, as there are so many variables that determine how quickly a Web page appears. And if the difference boils down to just a half-second or so, does that really matter? In any case, I looked for any major anomalies, such as pages that were especially fast or especially slow with or without a particular plug-in running.A few considerationsKeep in mind that a blocker may not always be able to distinguish invasive Web elements from benign ones. For example, some can prevent social-media buttons from appearing, thus thwarting your attempts to "like" or tweet about something.There's one other consideration, and that's the funding behind the blocker. While most of the apps that I looked at are free or open-source, supported exclusively by donations, at least one, DoNotTrackMe, employs a freemium model (charging a subscription fee if you want advanced features), while Ghostery asks you to provide usage data. Of the six tools reviewed here, only Adblock Plus has an "acceptable ads" feature that allows advertising from Google and other paying companies, and it's turned on by default. But you can easily disable it if you want a totally ad-free experience.Speaking of which, it's one thing to protect your privacy, but should you really turn off the ads that pay for so much good online stuff? It's food for thought, and if you want a big-picture discussion of ad-blockers and how they may or may not impact the Web as a whole, you may want to read Robert Mitchell's Ad blockers: A solution or a problem?.AdBlockPrice: Free; accepts user contributionsCompatible with: Chrome, Firefox, Opera, SafariNot to be confused with Adblock Plus (which originated as a Firefox extension), AdBlock currently works with Chrome, Safari, Firefox and Opera browsers.What it does: Blocks ads, of course. With AdBlock running, you shouldn't encounter any banners, pop-ups or video ads. However, the plug-in makes no claim to prevent tracking.How it performed: Because AdBlock isn't compatible with Internet Explorer, I confined my testing to Chrome. The tool offers some useful toggles from its toolbar pull-down menu, including options to pause the plug-in, disable it for just the current page or disable it for the entire domain. This last could come in handy if you discovered a compatibility issue with, say, a site's comment system. I never encountered any such issues.Rather, AdBlock worked exactly as advertised, keeping ads at bay virtually everywhere I went. It made for a blissfully ad-free viewing experience at Crackle and YouTube. Hulu actually detected the presence of AdBlock and flashed a message asking me to enable ads for the site. After about 30 seconds, however, the message disappeared and the show began playing. So while I didn't have to actually watch the commercial, I didn't enjoy uninterrupted viewing.Also, AdBlock tallied just five blocked items at TMZ.com, while Adblock Plus counted 14. Why the difference? It's tough to say, because neither program indicates exactly what's been filtered. The only visible difference was that, while AdBlock reformatted the page content to compensate for eliminated ads, Adblock Plus left a few empty spaces.Bottom line: If you want a mostly ad-free online experience, this does the trick. But AdBlock isn't quite as privacy-minded as Adblock Plus, and Internet Explorer users will have to look elsewhere.Adblock PlusPrice: Free; accepts user contributionsCompatible with: Chrome, Firefox, Internet Explorer, Opera, SafariDon't let the name fool you; Adblock Plus is not a "pro" version of AdBlock. Rather, it's a very similar tool that just happens to have a very similar name. (In fact, the former predates the latter by a few years.) It's somewhat controversial because it accepts money from some large companies to allow their advertising through as part of its "acceptable ads" policy.What it does: Adblock Plus (commonly known as ABP) eliminates banners, pop-ups and videos from the sites you visit. It also disables tracking, though not by default.How it performed: It's easy to understand ABP's popularity, as it performed extremely well on virtually every site I visited. However, though slightly prettier than AdBlock (at least when you pull up its action menu), ABP lacks a couple of the handy tools found in its competitor. For example, you can't fully disable ABP without venturing into the settings, while AdBlock lets you "pause" it with a simple click.ABP effectively filtered the ads from the videos I played at Crackle and YouTube, but when I tried to stream an episode of "Party Down" from Hulu, ABP left me staring at a blank window. No ads played, but neither did the episode. After a refresh, it played the episode -- but didn't filter out the ads.It's curious that one of ABP's most highly touted capabilities, tracking protection, must be enabled manually. In fact, it was only by accident that I discovered it wasn't active: A link on the Features page directed me to the options screen where you add the protection.Bottom line: Though perhaps not the best add-on with "Adblock" in its name, ABP is definitely the best choice for Internet Explorer users. It keeps ads and commercials away, and optionally stops trackers as well.DisconnectPrice: Free; accepts user contributionsCompatible with: Chrome, Firefox, Opera, SafariDisconnect aims to keep you in control of your personal info and does so primarily by blocking all tracking requests. It has the slick design of a commercial product -- and in fact comes from a commercial software developer -- but relies on a pay-what-you-want model (and lets you portion your contribution to charity if you wish). The developer also offers apps for Android and iOS.What it does: Though positioned as a privacy tool, Disconnect also blocks ads. But it won't do anything about the commercials that appear in, say, YouTube videos.How it performed: Once installed, Disconnect treats you to a treasure-trove of information via its drop-down window. For any given page you visit, you get a summary of all the advertising, analytic, social and content requests made (and blocked) while it loads. For each of the categories you can click to reveal a list of the actual companies or sites that made those requests. It's informative and interesting, to say the least, but probably superfluous for most users.Likewise, Disconnect's visualization view shows a nifty interactive graph of the relationships between the current site and the various trackers. It's neat, but not something you're likely to use (or need) often. Of greater use, the status window shows how much time and bandwidth you've saved by using Disconnect.Instead of an on-off toggle, Disconnect gives you the option of "whitelisting" the site you're currently viewing, effectively permitting all the ads and other stuff -- though it still keeps a running tally of all those items, which is cool. Also, you can manually allow individual sites and services, assuming you'd want to for some reason.Bottom line: Disconnect insulates you from pretty much every site except the one you're viewing and filters out ads to boot. Even if you never bother with its pretty interface, you can take comfort knowing it's working behind the scenes.DoNotTrackMePrice: Free for basic version; $5\/month for Premium versionCompatible with: Chrome, Firefox, Internet Explorer, Opera, SafariThe only straight-up commercial product in the group, DoNotTrackMe (DNTM) takes a freemium approach to privacy: You get the basic anti-tracking features for free, while a more robust Premium subscription, which adds features such as password management, costs $5 monthly. The developer also offers apps for Android and iOS.What it does: DoNotTrackMe's name undersells its capabilities, as this plug-in not only blocks ads and trackers, but also provides basic password management and aliases (or "masks") for email addresses, phone numbers and credit card numbers. (These last two options require DNTM Premium.)How it performed: More features can mean more complexity, and DNTM has the steepest learning curve of any of the tools in the group. But it's worth the effort.For starters, you must register for an account, even for something as basic as accessing the status menu in your browser's toolbar. Once you do, you're presented with four basic options: Accounts (the password\/auto log-in manager), Wallet (storage of credit\/debit card info), Masking (creation of aliases of personal info) and Tracking (or, rather, tracker blocking). This last is obvious enough, but the other features require a bit of exploring -- and probably some visits to the online help guides.If all you want is the tracking and ad blocking, DNTM works well enough behind the scenes. Once you click through to the Tracking area of the options window, you'll see a list of the trackers blocked for that site -- with the option to turn off blocking for individual trackers or the entire site.Then there's a link to the Tracking Dashboard, which opens in a new tab and shows a graph with the total number of trackers blocked over the past 10 days. Interesting info, but I feel that it should have been integrated into the tool rather than requiring a visit to a whole new tab.I briefly tested the other features, such as password management, and they worked as advertised.Bottom line: Though a capable ad- and tracker-blocker with some nice extras, DoNotTrackMe feels unnecessarily complex. Even so, the credit-card alias option makes a strong case for subscribing to Premium.\tGhosteryPrice: Free; supported by optional "donation" of tracked dataCompatible with: Chrome, Firefox, Opera, SafariGhosts can't be seen, and Ghostery aims to lend you that kind of invisibility when you venture onto the Web, drawing on what the developers claim to be the Web's largest tracker database. It costs nothing, not even a donation, but Ghostery does engage in some optional, anonymous data-mining: Its opt-in Ghostrank feature collects data about the browser you use, sites you visit, trackers you've encountered, etc. Rick BroidaGhostery displays a numerical blocked-items counter in its toolbar icon, a click of which reveals a scrolling list of trackers.What it does: Right out of the box, Ghostery blocks tracking cookies and scripts. Within its settings, however, you'll find a number of additional blocking options: advertising, analytics, beacons, privacy and widgets. Within those categories, you can opt to block some, all or none of what Ghostery finds.How it performed: Ghostery makes a good first impression with a helpful tutorial that appears the first time you click its toolbar icon. The second impression? Less good: By default, an ugly purple box appears as it identifies trackers on each site you visit. You can turn this off, but it's an unwelcome, unnecessary distraction that shouldn't be on to begin with.Like most of the other blockers, Ghostery displays a numerical blocked-items counter in its toolbar icon, a click of which reveals the plug-in's full menu. That menu consists of a scrolling list of trackers, each with a brief description of what it is (advertising, analytics, etc.) and an on\/off toggle. This makes for very easy customization for any given site and helps you learn how different elements can affect what you're seeing.For example, if you know a particular site uses Livefyre for its comment system, and you suddenly find the comment window has disappeared, it's a simple matter to toggle off the Livefyre blocking from within Ghostery's drop-down menu.On the other hand, this kind of granular approach makes Ghostery feel less automated than other tools, as it almost forces you to study and customize the various kinds of blockers. Indeed, after I'd enabled ad blocking, I found that YouTube videos played without commercials (bonus!), but Vevo music videos wouldn't play at all. To figure out a workaround took some toggle trial-and-error.Bottom line: Assuming you can get past the irony of a privacy-minded plug-in that supports itself by collecting usage data, Ghostery offers robust blocking capabilities -- but definitely requires some learning and customization.Privacy BadgerPrice: Free; accepts user contributionsCompatible with: Chrome, FirefoxA project of the Electronic Frontier Foundation (EFF), Privacy Badger is arguably the most altruistic ad- and tracker-blocker you can get. The very goal of the EFF is to "defend civil liberties in the digital world" -- in this case, by preventing advertisers and others from tracking your Web movements.What it does: Based on Adblock Plus code (but with a very different implementation, and limited to just Chrome and Firefox), Privacy Badger screens out the usual suspects: ads, third-party images, scripts and all manner of trackers.How it performed: In a word: mediocre. Privacy Badger didn\u2019t block banner ads at sites like Facebook and YouTube, while the ads it blocked elsewhere were represented by ugly gray boxes with pixelated sad-face icons in the center. It did strip the commercials from YouTube videos, but not those on Hulu.From a usability standpoint, Privacy Badger aims to keep things simple -- with mixed results. There are no global settings (other than enable\/disable), the idea being that users shouldn't have to monkey with customization. That's a nice change from, say, Ghostery, but perhaps it goes too far. Indeed, the tool offers no settings or controls whatsoever other than a three-position slider for each tracker it detects.Those positions are red, yellow and green, which stand for "block a domain," "block cookies" and "allow a domain," respectively. For each site you visit and each tracker detected, Privacy Badger sets each switch as it deems logical. But how do you know if you should change, say, "apis.google.com" from yellow to red? And why does a site like TMZ show so many trackers set to green?Thankfully, it's not necessary to make changes unless you run into some kind of obstacle, like a comment system not working properly. But for novice and even some tech-savvy users, Privacy Badger sometimes raises more questions than it answers.Bottom line: Limited compatibility and customization options hamper a tool that's simply not as effective as other blockers, and therefore hard to recommend.ConclusionIs there one ad-blocker or privacy protector that really stands out from the rest? Not really.If you're already using one of these products (or something similar), there's probably not much incentive to switch. Indeed, I've been running AdBlock for the past couple years, and while I found myself impressed with Disconnect's aesthetics, ultimately I decided to stay with AdBlock.Internet Explorer users have just two options, Adblock Plus and Ghostery, and to all but the most tech-savvy users I recommend the former. For everyone else, AdBlock and Disconnect do a superb job blocking ads and protecting your privacy.One reminder, however, as for the ads -- remember: Someone has to pay for great content like this.