Some sites use it to add extras to their webpages that can be used via a browser add-on or plug-in.

BBC: Oracle issues patch for Java loopholes

One such technology is Third Voice, a browser add-on that lets anyone stick virtual Post-it Notes on any Web page, for the whole world to see.

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You may need to check the settings on your browser add-ons to ensure they aren't blocking the player or Flash.

BBC: Your guide to the BBC Embedded Media Player

It is possible this software, or similar browser add-ons and extensions, are affecting the appearance of BBC embedded video on your PC.

BBC: Your guide to the BBC Embedded Media Player

Another change was a spell checker that keeps an eye on every bit of text typed in almost any Firefox browser box be it in a web-based e-mail program or an add-on that lets people post blog updates directly.

BBC: NEWS | Technology | Firefox browser for web 2.0 age