# What is an ATS? Applicant tracking systems explained > What an applicant tracking system is, what it does with a resume, whether it really rejects applicants automatically, and how it differs from a screening tool or HR software. Michael at SortTheStack, October 14, 2026. Original: https://sortthestack.com/blog/what-is-an-applicant-tracking-system **An ATS, or applicant tracking system, is software that manages hiring from the moment a job is posted to the moment someone accepts an offer.** It collects applications in one place, keeps track of where each applicant is in the process, and records what happened to them. The "tracking" in the name is the core of it: an ATS is a shared record of every applicant, not a judge of them. People sometimes say "application tracking system". It means the same thing. ## What an ATS does Vendors' feature lists vary, but the core is consistent: 1. **Posting the job** on a careers page and sending it to job boards. 2. **Collecting applications** from those boards, the careers page and email into one list per job. 3. **Reading the resume into fields.** This is called parsing. Workable's help centre, for example, says it scans uploaded resumes for the applicant's name, email and contact details, social media links and photo, and fills them into the applicant's profile. 4. **Moving applicants through stages** such as new, phone screen, interview, offer and hired, with notes and history at each step. 5. **Emailing applicants**, usually from templates. 6. **Scheduling interviews** and collecting interviewers' feedback. 7. **Reporting:** how many applied, from where, and how long each stage took. Larger plans often add offer letters and e-signatures, onboarding, background check integrations, and AI features that summarise or rank applicants. For which of those a small business needs, and what they cost, see [do you actually need an applicant tracking system?](https://sortthestack.com/blog/do-you-need-an-applicant-tracking-system) ## What happens to your resume in an ATS For applicants, the worry is usually that "the ATS" will throw their application away before anyone reads it. Here is what actually happens to an application in a typical ATS: - **It is stored and parsed.** The file is kept, and details are extracted into the profile. Parsing can go wrong with unusual layouts, which is a real reason to keep a resume simple, but the original file is still there for a person to open. - **It may be asked knockout questions.** Many application forms include screening questions such as "Are you legally able to work in this country?" or "Do you hold this licence?" An employer can set a wrong answer to reject or flag the applicant automatically. This is the clearest case of an ATS rejecting someone, and it applies a rule a person on the employer's side chose. - **It can be searched and filtered.** Recruiters can search applications by keyword or filter by answers. An application that doesn't use the words they search for may never come up, even though nothing rejected it. - **It may be ranked or summarised by AI**, if the employer uses that feature. How that works, and how much it explains, differs a great deal between products. ### About "75% of resumes are rejected by an ATS" This figure is repeated widely, usually with no source. We couldn't find any study or published data behind it, and the articles that repeat it don't link to one. Treat it as unsourced. There is good evidence of a related, real problem. In a 2021 survey of 2,275 employers by [Harvard Business School and Accenture](https://www.hbs.edu/ris/Publication%20Files/hiddenworkers09032021_Fuller_white_paper_33a2047f-41dd-47b1-9a8d-bd08cf3bfa94.pdf), most employers using recruiting software relied on it to filter or rank applicants, and 88% of those said their process screened out qualified high-skills candidates at least some of the time because they didn't match the exact criteria in the job description. The cause there is narrow, rigid criteria applied mechanically, not a fixed rejection rate. ## ATS, screening tool and HR software: the difference These three get mixed up because some products do more than one: | Software | What it's for | Typical examples of what it holds | | ------------------------------- | ------------------------------------------------------- | ------------------------------------------------------- | | Applicant tracking system (ATS) | Running the hiring process and keeping the record of it | Jobs, applicants, stages, emails, interview feedback | | Screening tool | Reading applications against the job's requirements | Requirements, assessments of each application, evidence | | HR software (HRIS) | Managing people once they're employed | Employee records, payroll details, time off, documents | An ATS answers "where is everyone in the process?" A screening tool answers "who should I read first, and why?" HR software takes over once someone is hired. ## Do you need one? If you hire continuously, across several jobs and several people making decisions, an ATS earns its cost. If you hire a few times a year, a [spreadsheet tracker](https://sortthestack.com/blog/applicant-tracking-spreadsheet) often does the tracking part well, and the hard part is reading the applications. Our [full guide](https://sortthestack.com/blog/do-you-need-an-applicant-tracking-system) has a decision table and verified prices. ## Where SortTheStack fits **SortTheStack is not an ATS**, and you don't need one to use it. It reads every application against requirements you set, shows the evidence for each one, and helps you decide who to read first. If you already have an ATS, it works alongside it; if you don't, it works on its own. [See how the screening works](https://sortthestack.com/product). ## Sources - Workable Help Center, [Uploading candidate resumes / CVs](https://help.workable.com/hc/en-us/articles/115012661408-Uploading-candidate-resumes-CVs-Individual-and-bulk-options), accessed 13 October 2026. - Fuller, J. B., Raman, M., Sage-Gavin, E. and Hines, K. (2021), [_Hidden workers: Untapped talent_](https://www.hbs.edu/ris/Publication%20Files/hiddenworkers09032021_Fuller_white_paper_33a2047f-41dd-47b1-9a8d-bd08cf3bfa94.pdf), Harvard Business School and Accenture.