Lookup up from Sheet 1 in Sheet 2 and display additional value in Sheet 1 when match

I have spent a day reading forums and trying different formulas and have decided it is just time to ask.

Sheet 1 contains over 20000 lines
Sheet 2 contains 9000 lines

Column A in sheet 1 contains values to match in Column A of Sheet 2, they are alphanumeric.
When a match is found, I want the value in column B of Sheet 2 to display in Column B of Sheet 1, next to the matching value in Column A.

It seems so simple to me but I cannot get anything to work.

I appreciate assistance from others. Thank you!

I would use, in B2 of Sheet1

=IFERROR(VLOOKUP(A2, Sheet2!$A$2:$B$10000,2, False),"")

If you are not getting matches that you think you should get, these are the most likely reasons
1. One is stored as a number and one as text. Check by typing this formula into an empty cell where the value you are interested in is in A12 =ISNUMBER(A12)
2. One or the other has spaces or other invisible characters before or behind them
Hope that helps

It did work, removing text from post and will update original post. Thank you!