Other Factors

As the landscape of the Web changes, there are new factors that can undermine performance and availability or make user experience harder to monitor. Here are just a few.

Browser Add-ons Are the New Clients

Browsers can be extended in two main ways using what Mozilla refers to as add-ons. The first category of add-on—known as extensions—affects how a page is loaded and displayed. One extension, Greasemonkey (https://addons.mozilla.org/en-US/firefox/search?q=greasemonkey&cat=all), is a scripting platform that can modify pages as they’re loaded, letting visitors customize how a site behaves within the browser.

Extensions may separate you from the user experience. Visitors may be playing a game such as WebWars or PMOG instead of interacting with your content. Browsers may be running the NoScript extension to avoid running scripts from untrusted sites. Extensions may also interfere with your JavaScript instrumentation of a page or break it entirely. However, extensions are still running within the browser, unlike the other form of add-on, known as a plug-in.

The Web has evolved in ways its creators couldn’t foresee, and today it’s the platform for broadcast media, gaming, human interaction, and more. Plug-ins are part of what makes this possible. They’re standalone software applications like Java, Quicktime, Windows Media Player, Adobe Acrobat, and Flash. Your browser delegates work, such as playing an audio file, showing a video, or displaying a document to them.

Plug-ins ...

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