Which is correct 80s or 80's?

Answer 1

"80s" is correct. The apostrophe is not needed and adding it is a common mistake. The confusion seems to arise from the use of the numeral 80. If one considers that "80s" is spelled "eighties", it is clear that no contraction or possessive is involved, hence no apostrophe is required. However, in the case where a possessive is actually required - for example, if one means to say something like "I like the version of U2 from the 80s." - the apostrophe would come after the "s" (not before), as in, "I like the 80s' version of U2."

Answer 2

The correct format is '80s' without an apostrophe. This is the standard way to refer to the decade of the 1980s.