Originally posted by AJ4LIFE616 is the mainstream reality of the marvel universe, it is where the events and characters that are reffereed to as canon are. The other worlds have different designations, such as ultimates or the MC2 universe. Each of these other realities diverged from 616 at some point in time. Some place where a different posability occured. Most of these are showcased in the Marvel "What if" series where alternate posabilities of what could have happened occured.
ok im shit with marvel wats all this 616 stuff and 982 its confuseing
For example Spider-girl's world (982) was shown in Marvel What-if #105 February 1998.
The numerical designation comes from the month and year in which the world was showcased. in the case of 616 it was with Fantastic four I#1 June 1961 the year digits are used firt 1961 and then the month. june being the 6th month is 6 so 616.