sorry in advance if this gets asked often, but how do i get into trains and railways as a hobby? i see trains, whether in real life or in media, and always think they're the coolest fucking thing on the planet. but when i go to learn more, i feel a bit intimidated by all of the information that's out there. there's lots of terms i don't understand (what's a multiple unit? and a pacer? shit like that), and there are SO many trains to learn about. where does a guy start?

i'm mostly interested in british trains and britain's railway, but i'd also like to learn a bit more about america and japan when i've built up the basics about british stuff. can any of you guys please give advice? would be extremely grateful. thanks!