When a recruiter opens their ATS to find candidates, they're not scrolling through every application. They're searching. The same way you'd search anything: type in a word or phrase, get a list of results.
Understanding this changes how you think about your resume entirely. The question stops being "does my resume look impressive?" and becomes "will my resume show up when they search?"
How recruiters actually search
Most recruiters start with the job title. "Product Manager," "Senior Software Engineer," "UX Designer." They narrow from there using must-have skills, certifications, or tools like "Salesforce," "PMP," "React," "Google Analytics."
Some use boolean search operators. "Product Manager AND (Salesforce OR HubSpot) AND SaaS" is a real search a recruiter might run. If those terms aren't in your resume verbatim, you're invisible to that search, regardless of how well your experience actually matches.
Where keywords come from
The job description is your answer key. Companies write job descriptions to describe exactly who they want. Read it twice.
First pass: note every technical skill, tool, platform, and certification mentioned. These are your hard keywords.
Second pass: note the soft skills and business concepts they emphasize. "Data-driven decision making," "cross-functional teams," "go-to-market strategy." These show up in searches too, and they signal cultural fit.
The keywords that get searched most often
Job titles. Include current and past job titles that relate to what you're applying for. If you've been a "Growth Manager" applying for a "Head of Marketing" role, make sure "marketing" appears prominently throughout your experience.
Specific tools and platforms. "HubSpot" beats "CRM software." "Figma" beats "design tools." "Snowflake" beats "data warehousing." Recruiters search for the specific thing, not the category.
Certifications. List them in full and abbreviated form. "Project Management Professional (PMP)" covers both the acronym and the full phrase. Either might get searched.
Industry terminology. Finance has "P&L," "EBITDA," "portfolio management." Tech has "API," "CI/CD," "agile." Use the words your industry actually uses, not layman descriptions of the same concepts.
Where to put keywords
The natural places are your skills section and bullet points. Don't stuff keywords. "Managed SQL SQL SQL databases" doesn't help anyone and looks bad if a human does read it. But if you have real experience with a skill, there's no reason not to name it directly.
Many people add a "Core Competencies" or "Technical Skills" section at the top specifically for this purpose. It works well: it's fast to scan, easy to customize per application, and gets picked up in searches.
A simple process
Copy the job description into a document. Highlight every skill, tool, and term that describes something you've actually done. Then open your resume and check: is each highlighted term present? If not, add it where it honestly fits.
It takes ten minutes. It's the single highest-leverage thing you can do for any application, and almost nobody does it consistently.