What is SATs?

Hello there, could you please explain something to me? I've been hearing a lot about SATs recently and I'm not quite sure what they are. Could you clarify for me what SATs stand for? Are they related to education or something else? Also, if you don't mind, could you elaborate on the purpose of SATs and maybe give me an example or two to help me understand better? It would be really helpful if you could provide some context as well, like where they are typically used or who takes them. Thank you in advance for your assistance!