Every Google Ads account shows ads for some searches it should never have matched. Someone looking for a job, a free template or a competitor's phone number clicks your ad, and you pay for it. Negative keywords are how you stop that from happening twice.
What a negative keyword does
A negative keyword tells Google not to show your ad when a search contains that word or phrase. Add free as a negative and searches including it will no longer trigger your ads. It is the opposite of a normal keyword, and it is the most direct control you have over where your budget is not spent.
Where to find them
The search terms report lists the actual searches that triggered your ads. Read it regularly and look for patterns: job seekers, students doing research, people wanting free or do-it-yourself options, searches for other cities and searches for products you do not sell. Each irrelevant term you find is a negative keyword waiting to be added.
Common negatives for service businesses
Some negatives apply to almost every local service account. Words such as jobs, careers, salary, course, training, free, cheap, template and DIY often signal someone who is not looking to hire. Add the names of cities you do not serve. Be careful, though: check that a word is not part of a search you do want before you block it.
Negatives are stricter than you expect
Negative keywords do not automatically cover close variations the way normal keywords do. If you block the singular, the plural may still get through, so add both, along with common misspellings. Negatives also have match types. A broad negative blocks searches containing all the words in any order, while an exact negative blocks only that precise search.
Keep the list organised and current
Build a shared negative keyword list for terms that apply across the whole account, and add campaign-specific negatives where needed. Review the search terms report weekly at first, then at least monthly. New irrelevant searches appear all the time, so this is ongoing maintenance, not a one-time setup task.
Adding negatives is unglamorous work, and it is some of the most profitable work in an account. Weekly search term reviews are part of how we manage campaigns for our clients.