One of the most useful websites I’ve found over the years is also one of the least known. In the interest of spreading knowledge, I wanted devote this entry to the Wayback Machine, which is run by the nonprofit Internet Archive. Basically, they are trying to keep an archive of the entire internet.
https://web.archive.org/
If a website is taken offline, or if the web owner changes something, there’s a good chance that the old version was saved by the Wayback Machine. This has saved my bacon a few times. It’s also just generally useful. For instance, the old Soundstage Rhythm Orchestra website that I used to run is gone, but you can still access the archived version of it – that’s what is linked from my Ensembles page.
Of course, it’s not a perfect archive. Some sites slip under the radar, and they don’t always catch embedded documents or files. It will load a lot slower than the original site. Also, if something is in a password-protected area, it won’t get caught. But if you’re ever trying to find something that seems to have disappeared from the web, the Wayback Machine is a good place to start.