Stoner is a slang term for individuals who consume cannabis as a recreational drug. There are many different types of stoners.
The word "stoner" generally holds a highly negative connotation amongst those that buy into anti-cannabis propaganda. Stoners are often stereotyped as shiftless layabouts who live in their parents basement and randomly set their shit on fire.
There are those, however, that take pride in their title as stoner and use the term in a positive way. Others think the term stoner applies only to people who smoke "too much".