If writing documents was once the primary function of a PC, then today it's to access the Internet. It's therefore fitting that there be so many useful free Internet applications available. Most popular among these would have to be Firefox, the most popular Internet browser besides Microsoft's own offering that has the distinct advantage of being installed on every Windows PC on the planet.
As for Firefox, its many qualities are well documented. A thriving community has meant there's a massive collection of extensions for the browser, adding all sorts of specialised but very useful features. Tabbed browsing is a given these days but its here and very welcome it is too, while on the whole Firefox does a good job of combining the ease of use of a basic browser with the power and flexibility that serious users require through its myriad of extensions.
If Firefox has a problem it's in resource use and if this is a concern for you, the lauded but less well known Opera will be of interest. Though it lacks the size of community that Firefox enjoys, many of the features included in extensions for Firefox are included as standard in Opera. Moreover, as already implied, it's less resource hungry and is generally regarded as faster in both application performance and webpage loading. Accessibility options are also a strong point, with extensive support for page zooming, voice control and mouse gestures.
Paradoxically, its main weakness is a result of its other strengths, a strict adherence to web formatting standards. This adherence to the rules means websites sometimes come out badly when using Opera, not because of Opera but inadequacies in the website programming. Workarounds have been implemented in recent versions, but some problems do remain. Opera is also sometimes criticised for its interface, which isn't as streamlined as some of its peers.
Having dealt with browsing programs, another staple of the Internet these days is the instant messenger. There are lots of them too, with the likes of MSN, Yahoo, AIM, ICQ and plenty of others all competing with each other. What better then, than a single program that can access them all? There are a few programs capable of this, but the best to our mind is the excellent freeware app: Pidgin.
Previously known as GAIM before it was kindly asked to change the name to something less familiar, it supports a massive range of messaging services, all of which can be run concurrently in the same process. Its only real weakness is a lack of support for some services, while some aspects such as file transfers aren't as efficient as they might be. Nonetheless, if basic IM functionality is all you need and you want to use several different services, Pidgin is the way to go.