What does xd mean when Texting?

It is an expression used repeatedly in emails and text messages denoting cheer and laughter. XD represents more of an emotion, in which ‘X’ implied for closed eyes, and ‘D’ depicts an open mouth.

It is primarily used when people want to signify that they are laughing out so loud, even their eyes are closed.

You can use it to add laughter and signify happiness. For instance; You have made my day by letting me know this funniest thing ever! XD.