An ATS (Applicant Tracking System) is the tool that centralizes a hiring process: posting jobs, receiving and screening applications, tracking each candidate stage by stage, communicating with managers and reporting.
In practice, each open role becomes a pipeline in columns (application, HR interview, technical test, final interview, offer). The ATS keeps the history of exchanges, schedules interviews, sends replies and extracts information from resumes (parsing). Many now offer AI-assisted matching or writing features.
There are ATSs for companies, designed for in-house HR teams and often paired with a careers page (Greenhouse, Lever, Teamtailor, Workday), and tools for recruitment agencies, which add a CRM layer to manage clients and assignments. The choice depends on hiring volume and the number of people involved.
Why it matters when hiring
An ATS does not hire for you: it makes the process visible and measurable. On the candidate side, keep in mind that automatic keyword screening often filters out good tech profiles with unconventional resumes. If you are hiring a recruiter or talent ops person, ask how they structured a pipeline and which metrics they tracked, rather than for the list of tools they know.