How do you put your bus pass on your phone?

I'm curious to know, how exactly does one go about putting their bus pass on their phone? Is there a specific app or service that needs to be downloaded? And what's the process like, from start to finish? Do you have to provide some form of verification or identification to LINK your bus pass to your phone? Is it a seamless experience, or are there any potential roadblocks or complications that one should be aware of? I'm eager to learn more about this process and how it can make commuting by bus even more convenient.