Personal information displaying codes.

Are there any codes that display the viewer user's personal information? Like, a member named 'John1873' is viewing a HTML page, and it says: "Hello John1873, welcome to my page!", if a member called 'SmileyGuy' views the HTML page, it says: "Hello SmileyGuy, welcome to my page!"
Shortly - A code that shows the viewing user's certain personal information, ex. Username, avatar and so on.

I hope you understand what I'm trying to say

I think you can use the PHP variables to make something up https://help.forumotion.com/tricks-tips-f32/list-of-variables-t48637.htm?highlight=php+variables

jake66 wrote:I think you can use the PHP variables to make something up https://help.forumotion.com/tricks-tips-f32/list-of-variables-t48637.htm?highlight=php+variables

Thx, ill try to figure out how to use these variables to be usefull for me