What are Bitcoin ATMs?

Could you elaborate on the concept of Bitcoin ATMs? I've heard of them but am not entirely sure how they function within the cryptocurrency ecosystem. Are they similar to traditional ATMs where one can withdraw cash? Or do they offer a different service entirely? Are there any specific requirements or steps one needs to take in order to use a Bitcoin ATM? Additionally, are there any security considerations one should be aware of when utilizing these machines? I'm curious to understand the full scope of Bitcoin ATMs and how they contribute to the cryptocurrency landscape.