|AMA||Ask me anything|
|TIFU||Today I F***ed Up|
|OOTL||Out of the loop|
|BIFL||Buy it for life|
|TIL||Today I learned|
|LPT||Life Pro Tip|
|FTFY||Fixed that for you|
|Blursed||Blessed and cursed|
YouTubers and Twitch streamers who ask you to sub to their channel want you to "subscribe." Subscriptions work a bit differently on each platform, but on both, they're a way of showing creators your support.
Subscribing to a YouTube channel is free. When you subscribe to a YouTube channel, you get notified when that channel posts more videos, and its new videos show up on your Subscriptions feed. If you watch a channel's videos regularly, you may want to think about subbing to it.
In contrast, you have to pay to sub to a Twitch channel. When you sub, the streamer whose channel you subscribed to receives some of the money you pay. In return, you receive channel-specific perks, like custom emotes, badges, and ad-free viewing.
On both platforms, sub may also be used to refer to a "subscriber." For example, a streamer may ask you to "become a sub" - which means they'd like you to become a subscriber to their channel.
|Twitch||Video game streaming website|
|Raid||To send viewers to another streamer's stream|
|GRWM||Get ready with me|
Redditors often use sub as an abbreviation for subreddit. Subreddits are topic-specific sub-forums, in which users interested in that topic can create, read, and comment on posts. Reddit is comprised of many, many subs - there is a subreddit for nearly every interest you could imagine.
For example, those who are into DIY projects can join the r/DIY subreddit, while those who want to follow and comment on world news can join r/worldnews. Some subs, such as r/AITA and r/explainlikeimfive (ELI5), are very active communities. Others, such as the sub for your local municipality (there likely is one), are often quieter.
What else might sub mean on Reddit?
While you "join" subreddits these days, you used to "subscribe," or "sub," to them. This repetitive and slightly unclear terminology ("you should sub to the NFL sub") was confusing, which is one of the reasons "subscribe" was changed to "join."