Tabletop role-playing games are the broader and incredibly diverse world around and away from Dungeons & Dragons, games where a group of people sits around a (virtual) table, with one usually guiding the story and (role)play through adhering to rules and describing the world and its characters, while the others play a main character each ("As your party crosses the threshold of the forest, the world seems to almost too quickly get darker and more quiet. Your flashlights all suddenly fail, and in a few steps further, you hear a strange sound permeate the air. It's reminiscent of.. howling, but wrong somehow. What do you do?" – "I would like to try and keep my cool. Then, I'll see whether I can discern anything about the cry using my training." – "Okay, please use two six-sided dice to roll for your Sharp and see whether you succeed.").
The hobby ranges from dense games with a tactical side to them, through old-school-style dungeon crawlers and games that work more as story generators, to minimalistic few-pagers you can get going in an afternoon, with a lot in between. And thanks to the internet, you can now get into one with as little as a connection and, unless you choose play-by-post, a microphone (though whether the convenience of online play outweights the energy of an in-person game is up to you to decide).
I've played a number of TTRPGs in the past, both as a player and as a gamemaster. Something about them is simply so alluring.
My favorite RPG memories come from a series of three campaigns I ran that all shared some players. The first two were set in the world of Half-Life 2 and used a hack of the 24XX system I had thrown together, with the last (and unfinished) one running in Monster of the Week.
Currently, I have a group running a classic fantasy adventuring campaign, with whom it seems I might be finally discovering my GMing style and how I can have more carefree fun with these games. And I'm reading way more TTRPG books, which also helps – as of now mostly their core rulebooks, but I'm also interested in the various supplements.
Historically and conceptually related are tabletop wargames – both of the board and miniature variety – and LARP. Currently, I actively participate in neither, but that might one day change.