Is it safe to run your pc 24/7

Is it safe to leave your pc on 24/7 ?

Yes.

When it starts to lag, then give it a rest.

PCs can stay on for practically ever, but you do need to shut it down every once in a while to clear the RAM because it becomes slow after a while. The best thing to do is leave it on idle of sleep mode. I dont recommend you leave PCs on tho unless your running a server.

It is but leaves it vunerable to virus attacks so get an antivirus

Good rule of thumb is if you aren't going to use your computer for the next 6 hours turn if off. leaving it on will ware it down faster, not by much but it will, but turning it on and off every few hours will ware it down much faster so leave it on if your only going to not use it for a few hours.

Also you can program your computer to restart every 24 hours if you leave your computer on all day long like I do.

It may be safe but hardly anyone realizes the danger side of leaving them on that long. For example it has been in news that people (rarely admittedly) had an electric fault for leaving their computer on for ages especially, it can blow the computer up and harm.

No way It can be safe. Only servers of hosting companies a
re safe in that respect .

well my uptime is currently verging on a month. alot of restarts due to new programs but all in all its been running for close to a month straight