What are bitcoin casinos?

Could you please elaborate on the concept of "bitcoin casinos"? I'm curious to know how they operate differently from traditional casinos. Do they accept only bitcoin as a form of payment? Are there any specific advantages or disadvantages to playing in such casinos? Additionally, how secure are these bitcoin casinos, and what measures do they take to protect players' funds and personal information? Finally, could you provide some examples of popular bitcoin casinos that are currently operating? Thank you for your insights!