What Is an ATS and How Does It Work

An Applicant Tracking System (ATS) is the software companies use to manage their hiring pipeline. When you submit a resume through a job board, a company career page, or an email link, that document passes through an ATS before any human recruiter reads it. Systems like Workday, Greenhouse, Lever, iCIMS, and Taleo handle millions of applications each year for employers of all sizes.

The ATS performs two core functions: it organizes applications into a searchable database and ranks candidates based on how closely their resumes match the job description. When a hiring manager searches for candidates for a "Senior Data Analyst" role, the ATS surfaces the resumes that scored highest for that requisition. If your resume does not parse correctly or lacks the right keywords, it lands at the bottom of those results — or gets filtered out entirely.

A single corporate job posting can attract 200 to 500 applications, so the software pre-screens based on criteria the employer configured: required skills, job titles, education level, years of experience, and specific keywords from the job description.

Why Your Resume Gets Filtered Out

Resumes get rejected by ATS software for specific, identifiable reasons. The most common cause is a mismatch between the language in your resume and the language in the job posting. If a job description asks for "project management experience" and your resume says "managed projects," a basic ATS may not recognize the equivalence. These systems rely on literal text matching, not semantic understanding.

Formatting problems represent another major filter. ATS parsers strip out most visual elements when processing your resume. Text boxes, tables, graphics, or multi-column designs often cause the parser to scramble content — your contact info and work history can land in the wrong fields or disappear entirely.

An ATS expects a predictable structure: Contact Info, Summary, Work Experience, Education, Skills. When it encounters a header like "My Career Journey" instead of "Work Experience," the parser may not know where to file that content. Unconventional job titles, undefined acronyms, and images replacing text cause similar problems.

How ATS Scoring Actually Works

ATS scoring is not a single universal metric. Each system uses its own algorithm, and employers configure weighting based on what they prioritize. Most platforms evaluate resumes across several consistent dimensions.

Keyword match percentage is typically the heaviest factor. The system extracts key terms from the job description — required skills, technologies, certifications, methodologies — and checks how many appear verbatim in your resume.

Section relevance measures whether your content is structured so the ATS can categorize it. The parser needs to correctly identify your job titles, company names, dates, degrees, and skill lists. When these land in the right fields, your resume becomes searchable.

Experience alignment compares your listed roles and tenure against the job requirements. If the posting specifies "5+ years of B2B sales experience," the ATS checks whether your work history reflects that duration. Unclear role descriptions or dating gaps can hurt your score even when your actual experience qualifies you.

You can test where your resume stands by running it through a free ATS resume checker that simulates this parsing and scoring process.

How to Improve Your ATS Resume Score

Keywords That Matter

Keyword optimization for ATS is not about stuffing random terms into your resume. It requires identifying the specific language each job description uses and reflecting it back in your document. Start by pasting the job posting into a resume keyword matcher tool to extract the highest-priority terms. These fall into three categories:

Hard skills are technical abilities listed as required or preferred: programming languages, software platforms, methodologies, certifications. Each should appear in your skills section or woven into experience bullets.

Industry terminology includes acronyms, regulatory frameworks, or domain-specific language. A healthcare administration posting might reference "HIPAA compliance," "EHR systems," and "CMS guidelines." Using the exact acronym matters — writing "Electronic Health Records" when the posting says "EHR" can cause a mismatch.

The most effective approach is to create a master resume with all your skills and experience, then tailor a version for each application by swapping in the relevant keywords from that specific posting.

Formatting That ATS Systems Can Read

Stick to a single-column layout with standard section headers. Avoid tables, text boxes, merged cells, and any element that forces the ATS to guess reading order. A left-to-right, top-to-bottom structure parses cleanly every time.

Pick one professional font — Calibri, Arial, Times New Roman — and use it throughout. Keep sizes between 10 and 12 points for body text and 14 to 16 for headers. Save as .docx or text-based PDF, never as a JPG, PNG, or scanned image. Dates should follow one consistent format: either "Month Year" or "MM/YYYY."

Skills Section Optimization

Your skills section is a keyword zone that ATS parsers scan first. List skills under a clear "Skills" header, grouped by category:

  • Programming: Python, R, SQL, JavaScript
  • Tools: Tableau, Power BI, Google Analytics, Jira
  • Methodologies: Agile, Scrum, A/B Testing, Root Cause Analysis
  • Certifications: PMP, AWS Solutions Architect, Google Analytics Certified

Avoid vague entries like "strong communication" — they add no keyword value and waste space.

Real Example: Before and After ATS Score

A software developer named Marcus applied for a mid-level frontend role and received an ATS score of 32 out of 100. His resume used a two-column template with paragraph blocks and no mention of several technologies in the job description. The posting required React, TypeScript, REST APIs, unit testing, and CI/CD pipelines. Marcus's resume mentioned only "JavaScript" and "web development" — accurate but too generic to match.

After analyzing the gap, Marcus restructured his resume into a single-column format and replaced paragraphs with bullet-pointed accomplishments:

  • "Built and maintained customer-facing features using React and TypeScript, improving page load speed by 40%"
  • "Designed and consumed REST APIs to integrate third-party payment processing"
  • "Implemented unit testing with Jest, achieving 85% code coverage across the frontend module"
  • "Configured CI/CD pipelines using GitHub Actions for automated deployment"

He added a dedicated skills section listing React, TypeScript, REST APIs, Jest, GitHub Actions, CSS, HTML, and Git. On resubmission, his score jumped from 32 to 87. The changes took 30 minutes and involved no exaggeration — just alignment with the job description's language.

Common ATS Resume Mistakes

Using photos or logos. Any information in a photo, icon, or graphic is invisible to the parser, including your name if it appears only inside a header image.

Including tables for layout. Tables disrupt reading order. Content correct visually may extract as disjointed text, causing job titles and dates to separate.

Submitting non-text formats. A JPG or PNG resume is invisible to the ATS — the parser sees a binary file with no extractable text.

Placing contact info in headers or footers. Some ATS platforms do not parse document headers and footers. Keep your name, phone, email, and LinkedIn in the main body.

Checklist: ATS-Ready Resume

  • Single-column layout with no tables, text boxes, or graphics
  • Standard section headers: Summary, Professional Experience, Education, Skills
  • Saved as .docx or text-based PDF
  • Keywords from the job description included in context
  • Skills listed in a dedicated, clearly labeled section
  • Bullet points for work experience — no paragraph blocks
  • Consistent date format throughout (Month Year – Month Year)
  • Contact information in the document body, not in headers or footers
  • No images, icons, or photos
  • Job titles match or closely align with the target role

FAQ

What is a good ATS resume score?

A score above 70 indicates strong keyword and formatting alignment. Between 50 and 70 suggests moderate matches with room for improvement. Below 50 means critical keywords are missing or the document failed to parse. Use a free ATS resume checker to identify the specific gaps.

Do all companies use an ATS?

Most mid-size and large companies use an ATS. Small businesses may review resumes manually, but even those posting on LinkedIn or Indeed often receive applications through ATS integrations. Optimizing for ATS compatibility does not hurt your chances with manual reviewers.

Can ATS read PDF files?

Most modern ATS platforms parse text-based PDFs. Problems arise with scanned images, embedded fonts, or complex vector graphics. Export from Word or Google Docs as a standard text PDF — not from a design tool like Canva.

How many keywords should I include?

There is no fixed number. Incorporate every required skill and as many preferred skills from the job description as your experience supports. Keyword stuffing can backfire when a recruiter finds disconnected terms with no context.

Does ATS penalize resume gaps?

The ATS itself does not penalize gaps, but inconsistent or missing dates cause parsing errors that lower your score. List your dates honestly and consistently — leaving dates off is worse because the ATS may fail to categorize your experience correctly.

CTA

Ready to see how your resume scores? Run it through our free ATS resume checker to get a detailed breakdown of your keyword matches, formatting issues, and overall ATS compatibility. Then use the resume keyword matcher to compare your resume against any job description and identify the exact terms to add or adjust.