and often cropped up in the early days of the forum.
Modern computers are designed to run for very long periods without being turned off. Web servers are just computers (although some of them are pretty big and pretty expensive)and they run constantly - only being turned off very occasionally for essential maintenance.
Your computer can do the same thing if you want it to, and although something will fail eventually there are those who say that the components will benefit from not being constantly turned on and off; all those thermal cycles can lead to material fatigue and something that glorifies in the name of 'Chip creep'. The theory is that repeated heating and cooling cycles can cause a chip's pins to 'creep' out of the sockets, making for poor electrical contact.
All in all I'm in favour of leaving computers running. They use virtually no electricity on stand-by, and those in my office stay on from Monday morning until Friday evening. They get two days rest at weekends, but I don't, and nor does the machine I'm using to write this.