If you're using Google Sheets and you have two separate columns of data in which you're looking for matches, there's a pretty easy way to highlight the matched items. You can also do it the other way around and highlight items that don't match. You're typically doing this because your lists are long and you can't do it visually. However, for this example the lists are purposely small so it's easy to see.
We're going to do it through Conditional Formatting. Go to your menu, then to Format, and select Conditional formatting. The Conditional formatting menu options will pop up on the right-hand side and there's everything you need right here.
First, apply the conditional formatting to the range which, in this shared spreadsheet (which is also embedded near the end of this page), is C1 to C10. Note that the range is different in the video but the process is the same. You can select the range with your mouse or type it in as C1:C10.
At first, the range should be highlighted because it is set to highlight if it's not empty. Change this to a custom formula, which is at the bottom. Click on Custom formula is and then it gives you a box that's waiting for the formula.
You are going to be typing in a formula just like you're typing into a spreadsheet cell. One of the differences though is now Google Sheets is not going to help you. Once you start typing the function, no helper text will pop up to explain the function. If you want help, type the formula into a cell in the spreadsheet and it'll help you build it. Then, you can paste it into the custom formula box.
You want to use a function called MATCH. MATCH is going to look at each cell in the range and check to see if it exists in the other range that you specify. The first parameter that you want, it's going to do this one cell at a time, is C1. Now type a comma and Sheets will be looking for the range that you want to try to look up C1 in to see if it's a duplicate. You don't want this range to shift down every time it evaluates a cell on the right., so use dollar signs before the row numbers to fix the range as such
Next, your spreadsheet wants to know if this is going to be an exact match. Enter a 0 (zero) for yes so if it finds exactly Yellow. Now close it off with the parentheses. Your code should look like this:
The box that contains this function should have changed from red to blue meaning that the function is now a valid function. It should be working after the box turns blue. You can see it highlighted the color red in green because red is on the list on the left but it didn't highlight orange because orange isn't in that list. If you click done, you've highlighted everything that exists in the other list.
If you want to do this the opposite way, and highlight the items in this list that aren't in the list on the left, wrap your formula in the function called ISNA. The ISNA function is saying - look, if the MATCH function doesn't work, highlight it. Not if it does work. After the ISNA, put a parenthesis and then go to the very end and close it with the parenthesis.
View of Sheet with ISNA applied
After following this tutorial, you should be able to highlight matches or differences between two columns. If you have any questions, feel free to leave a comment below.