Most job seekers have heard that an "ATS" stands between their resume and a recruiter's eyes, and most have the wrong mental picture of what it does. An applicant tracking system is not a gatekeeper AI that judges whether you're qualified. It's a database and parsing tool: it pulls your resume apart into fields (name, job titles, dates, skills) so recruiters can search and filter a pile of applications quickly. The rejections happen when the parsing goes wrong, not because an algorithm decided you weren't good enough.
The most common failure mode is a resume the ATS can't read correctly, not one it reads and dislikes. Multi-column layouts, text boxes, tables, headers/footers with contact information, and graphics-heavy templates frequently get mangled when the system extracts text — a column layout can get scrambled into nonsense, or a skills table can simply vanish. Your experience might be excellent and still never reach a recruiter's screen if the parser mis-reads your job title as blank.
Skip the trick of stuffing invisible white-on-white keywords into the document. Most modern systems strip or flag it, and even when it slips through, a human recruiter who opens the file and sees a résumé that doesn't match what was "found" will simply discard it. The same goes for cramming in every possible keyword regardless of relevance — recruiters increasingly review the shortlist manually, and an obviously padded resume reads as dishonest, not thorough.
Formatting gets you past the parser; relevance gets you past the recruiter. Once your resume is correctly read, the actual decision comes down to whether your experience matches what's being hired for — which means tailoring your top bullet points to the specific role each time you apply, rather than relying on one generic resume for everything. The ATS determines whether your information arrives intact. What you put in it still does the real work.