BRB = be right back 馬上回來
BTW = by the way 順便提一下
2，4，B，U，Y = two，for，be，you，why
TTYL = Talk To You Later

Often times when people are texting to save time they shorten the words. we'll talk about some today.
大家經(jīng)常為了省時間用縮寫，今天我們就要聊聊這個。
It's used when you have to do something real quick but don't want to end the conversation.
當你真的不得不要去做另外一件事情，但是又不想結(jié)束現(xiàn)在的對話的時候就可以用啦。
It means 'by the way' we use it when we are maybe changing a subject or have to inform someone of something.
BTW和by the way意思一樣，想換一個話題或者要告訴別人一個什么事情的時候可以用。
Actually after someone send TTYL to you, but they won't really talk to you later.
一般別人給你發(fā)了TTYL后，他們不會真的等下還回來和你聊。