SyntaxBoom

This is is going to be the start of a list of useful links to various sites where you can get music or other sound effects. If anyone adds some gems, then they will be added to this post, so people don't have to go through every post.

NOTE: Many of these linked sites have not been checked for what contents they offer.
If they don't appear to be what is advertised, or look suspicious. Then PM an administrator so they can be removed.
So use at your own risk.

For a list of game art and texture libraries. See here (https://www.syntaxboom.com/forum/index.php?topic=26.0).
For a list of game development tools. See here (https://www.syntaxboom.com/forum/index.php?topic=25.0).
For a list of programming languages and tools. See here (https://www.syntaxboom.com/forum/index.php?topic=28.0).

Sound Library Sites
SONNISS (https://www.syntaxboom.com/forum/This%20is%20is%20going%20to%20be%20the%20start%20of%20a%20list%20of%20useful%20links%20to%20various%20sites%20where%20you%20can%20get%20textures%20or%20sprite%20images.%20If%20anyone%20adds%20some%20gems,%20then%20they%20will%20be%20added%20to%20this%20post,%20so%20people%20don't%20have%20to%20go%20through%20every%20post. %20NOTE:%20I%20haven't%20checked%20what%20contents%20some%20of%20these%20sites%20offer.%20So%20if%20they%20don't%20appear%20to%20be%20what%20is%20advertised,%20then%20PM%20an%20administrator%20so%20they%20can%20be%20removed.)
Open Game Art (https://opengameart.org/content/library-of-game-sounds)
A Sound Effect (https://www.asoundeffect.com/sound-category/sound-effects-genres/gameaudio/)
pixabay (https://pixabay.com/sound-effects/)

Music Library Sites
pixabay (https://pixabay.com/music/)

https://incompetech.com/music/royalty-free/music.html

https://soundbible.com/