Copyright term

For a work by a named human author, the standard term in the UK, the US and the EU is the author's life plus 70 years. Corporate and anonymous works run on a different clock: in the US, works made for hire get 95 years from publication or 120 from creation, whichever ends sooner. Sound recordings, films and broadcasts each have their own rules, and terms differ between the country a work came from and the country you upload in.

Two things catch creators out. Old does not mean free, since a 1930s song can still be in copyright and a modern recording of a very old piece carries its own fresh copyright. And an expired copyright does not clear a trademark, so a public-domain character can still be off-limits in your thumbnail.