What are the different type of welding jointsand how many ? (strongly not talking about body joints)

Wikipedia's Welding article covers the five basic joints and Guide to the 5 basic types of Welding Joints illustrates those as well as some combination joints. So how exactly many depends on what the instructor wants to hear. See American Welding Society standard A2.4:2007 for symbols.

Thank you Scleros for your help!