An Applicant Tracking System (ATS) is software that employers use to manage the hiring pipeline — from job-posting distribution to resume storage. When you apply online, the ATS parses your resume into structured fields (contact, experience, education, skills), then scores it against the job description using keyword matching and increasingly, semantic similarity.
Common ATS platforms include Workday, Greenhouse, Lever, iCIMS, and Taleo. They all share the same core constraint: your resume must parse cleanly. Multi-column layouts, tables, text boxes, headers/footers, and images frequently break parsing — which means the ATS silently drops key information before it ever scores your application.
The practical takeaway: use a single-column layout with standard section headings, mirror the job description's terminology, and test parse quality with a plain-text copy/paste or a free ATS checker before you apply.