excel cell comparison question

i have 1 column initially and will add more columns weekly,, the new column will be inserted adjacent to the ‘key’ data column,,the new column may be of different row counts so the rows will not always match up horizontally.. however i need to match up any equal values in column a and b’s column’s rows and extract these matching cells by rows on a new worksheet with only the matching cells being shown.. i’m having a tough time making a macro for this one.. any macro kings or queens out there?? thanks for any help,, at this point pick any crayon out of the clueless box,, thats my color.. johnb..