2. Extend Your Browser.

Extending the browser your working in relates to small applications that add to the browser capabilities, plug in's are similar but can be more related to search tools for other sites or search engines these are a little different in my mind they are a way to "plug in" to another site's /  search engine's search tools.

The name add on is used to generally describe these applications.  The range and scope of add-on's available these days is huge, there are two main browsers with add on capabilities these are Mozilla Firefox and Internet Explorer 7 & 8.  Firefox has a far wider array of add-on's and tools for the browser compared with Internet Explorer which has just seen the additions of add-on's in later editions.  I personally use Firefox for my main browsing and development and Internet explorer for any Microsoft Services that are not included with Firefox (I'm sure there is perfect add-on's available if I looked). Here are some images of the different approaches to adding an add on in Internet explorer and Mozilla Firefox. In Internet explorer the first addition was to be able to customise a search bar to your favourite Search engine shown here: 

The process is as follows, browse to the Find more providers page:

There are a selection of search engine's here or you can add a custom made one on the right of the page by following on screen instructions, there are now IE7 & 8 Add-on's as well as the search plug-in's. These can be accessed by the tools menu and select the Add-On's and then find more Add-on's the page for Microsoft approved Add-On's is shown below:

In Firefox the range of Add-on's is much greater and is becoming the development choice for a lot of web administrators. To start off you can also change the default search engine used inside the top right corner of the browser, you can also add more then one search engine to this area as shown below:

The Add-on's for Firefox can again be found under the tools menu within the browser the internal interface for configuring and now even searching out new Add-in's and Plug ins as shown here:

There is also a web page dedicated to the hosting of approved add on's this is a larger in my experience range of Add-on's and applications to enhance the browser's capabilities. The Web page is shown below:

Conclusion:

The capabilities to change and add a specific search engine to your browser has greatly enhanced the Internet 2.0 browsing experience,  It saves time and frustration by utilizing previously unused browser real estate.  Add-on's have extended the capabilities of the modern browser, allowing better debugging for Web site administrator right the way down to allowing a family slide show to stream with silverlight to the average end user.  I believe once discovered some of the wide range of Firefox add-on's

In the work place saving time usually means saving money so in that sense add on's are a very useful for saving time on Internet searches, and generally make the Internet browsing experience easier.  I believe that a lot of browser plug ins and add on's would be widely use in the IT industry and possibly even custom plug in's.