Level: Basic
Stray whitespace is invisible on screen but causes real problems the moment you try to match, sort, or deduplicate a keyword list.
The Excel Technique
The TRIM() function removes leading, trailing, and extra internal spaces: =TRIM(A2). CLEAN() removes non-printable characters that sometimes come through in a copy-paste from a PDF or web page: =CLEAN(TRIM(A2)) combines both in one formula, applied down the column and then pasted back as values.
Example Scenario
A keyword list copied from a PDF competitor report looks fine on screen, but a VLOOKUP against it keeps failing to find exact matches that clearly exist. The culprit turns out to be invisible trailing spaces and stray line-break characters carried over from the PDF's original formatting.
Where This Fits in Your Keyword Research Process
This kind of invisible formatting issue is one of the most common causes of "my formula isn't working" frustration in keyword spreadsheets, and it's worth checking for by default on any pasted-in list.
Next step: Use Normalize Whitespace from SeoWolf's Notepad to run the PDF-sourced keyword list through it before pasting into Excel, collapsing the irregular spacing and stray characters so your VLOOKUPs and exact-match formulas work correctly the first time.