Ellipses are a really good example of a case where the meaning is much different in chat than in standard written English. My favorite is the double dot, .. ,

Ellipses are a really good example of a case where the meaning is much different in chat than in standard written English. My favorite is the double dot, .. , which I often use with some friends because a period seems formal or angry, whereas a double dot conveys a thought/sentence but in a more open ended sense. I wouldn't chat with someone in a professional context in that way though, and I have no idea how common that particular usage is even. I think it's kind of like handwriting where people and groups develop a style and then it becomes second nature and hard to explain.