What It Is
A Google results page has two kinds of listing. Ads are marked Sponsored, and a business pays each time someone clicks one. Everything else is organic: pages Google chose because it judged them the best answer to the search. Organic SEO (search engine optimization) is the work of becoming that answer for the searches your customers actually make, like "water heater replacement Denver" or "tent rental near me."
How It Works
Google says it does not accept payment to rank a site higher. What it rewards, by its own account, is relevance and usefulness: a page that clearly answers what the person searched for, on a site Google can crawl and trust. In practice that comes down to a few things. A page for each service you want to be found for, written in the words customers use. Titles and descriptions that say what the page is. Content that shows real experience, like photos of your own work and answers to the questions customers ask on the phone. And links from other sites, like local news, suppliers, and neighborhood associations, which Google treats as a sign that others vouch for you.
Why It Matters for Being Found
An ad stops the day the budget does. An organic ranking keeps bringing calls while you sleep, and it gets stronger the longer it is tended. For most local businesses the right answer is both at once: run the ads that are already working while the organic pages are built, then turn the ad spend down as the organic results take over the same searches. Organic takes months, not days, which is why it is worth starting before you need it.