At the end of the day a computer is a very sophisticated bit of kit, but without applications it is nothing more than a fancy toy. We wouldn't have so many computers in the workplace or home if it weren't for the apps that drive adoption. In a very real sense, applications are the lifeblood of the computer industry.

The term 'killer app' gets tossed around quite liberally these days. Nearly every piece of software released seems to be pitched as having the potential to send shockwaves throughout the IT world.

In reality, there have been precious few applications which have truly changed the computing industry over the years. This week we examine a few of those true 'killer apps' and what they have meant to computing.

I do think that it was an industry-changing app, if not always for the better. Before the days of LOLcats and gossip blogs there wasn't much of a leisure experience connected with office computing.

When the hours started running long and attention spans started running short, office workers began to turn to games such as Minesweeper, Tetris and solitaire that came pre-installed on most workstations.

For most, these games were a nice release and only a minor hindrance to actual productivity. However, as with all good things, casual gaming could get out of hand. Nearly every office has the story about the one worker who seemed to spend six hours every day playing Minesweeper.

Iain Thomson: I meant what I said Shaun; it's a game, not an application. Nevertheless it's difficult to deny the impact of Minesweeper. One analyst firm estimated it had done more to damage office productivity than anything else in the computing world.

Like many successful games, Minesweeper is deceptively simple, but can be fiendishly difficult in practice. Since my boss reads this I would like to say that I never play the thing at all, oh no. Actualy I rarely play it at all, but that's not the point.

Minesweeper introduced a lot of office workers to computer games, and I'd argue that it didn't harm productivity that much. Everyone needs a break now and again after all.

Originally an engineering check function used in the early days of mobile phone development, SMS was left on the handsets and initially wasn't even charged for. Younger phone users discovered it and saw an immediate use. At one point the majority of texts were sent on Friday and Saturday nights, as people tried to find each other in nightclubs where conversation was impossible.

SMS is a special application because it has some key advantages. Providing the number is right the recipient will be unable to ignore the message because it appears automatically on their phone. It has also made reassuring relatives from abroad much cheaper than a phone call. If there's one downside its occasionally receiving a message like 'We need to talk.'

Shaun Nichols: As someone who has been unceremoniously dumped via SMS, I definitely agree that is has major drawbacks. The advantages, however, are far greater.

When one is at a crowded event such as a club or a parade, SMS is just about the only way to communicate. I can't count how many hours of searching for friends at clubs and concerts I have saved through text messaging.

It also has the advantage of allowing for a private conversation with a person when you don't want to tip off a third party. Scoff all you want, but we've all sent an SOS to have a friend come bail you out of a boring conversation or an unwanted advance while out on the town.

Considering how few people were familiar with the concept of SMS messaging 15 or even 10 years ago, the system has quickly become a vital method of communication for a very large portion of the general population.