Resume keywords are the skills, tools, methods, titles, certifications, and industry terms that employers use to describe the role. ATS software uses them to classify your resume, and recruiters use them to quickly decide whether your background is relevant.
The goal is not to stuff the page with repeated words. The goal is to prove that you have done the work the job requires, using language the hiring team already recognizes. Strong keyword optimization makes your resume easier to parse, easier to search, and easier to trust.