Applicant Tracking System (ATS)
An applicant tracking system is software that receives, parses, scores, and filters job applications before a human reviews them. Workday dominates the Fortune 500; Greenhouse and Lever own most of tech; iCIMS and Taleo are common in healthcare, retail, and government. Roughly 99% of Fortune 500 companies use an ATS (Jobscan, 2024). See the full What is ATS guide.
Resume parsing
Parsing is the step where the ATS reads your PDF or DOCX and extracts structured fields (name, email, employer, role, dates, skills) into a database row. Two-column layouts, tables, headers/footers, and graphics break parsing. ATSHack outputs a single-column PDF with standard section headers because that is what every major parser handles cleanly.
Keyword density
Keyword density is how often a job's required skills and verbs appear in your resume relative to its length. Most ATS scoring algorithms weight three signals: frequency (how many times a keyword appears), position (Skills section vs. buried in a bullet), and recency (current role vs. a job 8 years ago). Stuffing keywords doesn't beat structure; placing the right keyword in the right section does.
Knockout question
A knockout question is a required question in an application form that auto-rejects candidates without any human review. The most common knockouts: years of experience, work authorization status, willingness to relocate, and salary range. If you answer a knockout in a way the recruiter has flagged as disqualifying, your resume never gets scored — it gets archived.
Boolean search
Boolean search is the query syntax recruiters use inside the ATS database: AND, OR, NOT, quotation marks for exact phrases, and parentheses for grouping. Example: "python" AND ("AWS" OR "GCP") NOT "intern" returns mid-and-up Python engineers with cloud experience and excludes interns. The keywords on your resume have to literally match the recruiter's Boolean query — synonyms don't help.
ATS score / match score
An ATS score is a 0–100 number that ATS platforms (or third-party tools like Jobscan, Resume Worded, and the ATSHack free grader) generate to tell you how well your resume matches a job posting. There is no industry-standard scoring algorithm; every tool weights keywords, format, and recency differently. Treat scores as directional signal, not gospel.
Resume tailoring
Tailoring is rewriting a resume to mirror the keywords, structure, and emphasis of a specific job posting. The opposite of mass-applying with one generic resume to 200 jobs. Why tailoring matters →
Single-column resume
A resume layout with one vertical column of text and standard headings (Summary, Experience, Education, Skills). It's the format ATS parsers reliably handle. Two-column layouts often drop the right column or jumble the order in parsing. ATSHack outputs single-column by default.
Workday
The dominant Fortune 500 ATS. Long, multi-page application forms; aggressive parsing of work history into structured fields; case-sensitive matching for some certification strings. Workday will ask you to re-enter your work history in form fields after you upload your resume; both versions get scored.
Greenhouse
The standard ATS in tech and growth-stage startups. Cleaner parsing than Workday, more reliance on structured job-board data, integrates with LinkedIn Easy Apply. Greenhouse exposes a "Scorecard" feature where interviewers tag resumes by competency.
Lever
An ATS focused on candidate-relationship workflows. Common at Series B–D companies. Parses PDFs cleanly and exposes a structured candidate profile to recruiters. Lever has historically been more lenient with formatting variation than Workday or Taleo.
iCIMS
An enterprise ATS used by healthcare systems, retailers, and federal contractors. Older parsing engine; prefers DOCX over PDF in some configurations. If a posting on an iCIMS-powered careers page says "upload Word format," submit DOCX.
Taleo (Oracle Recruiting)
A legacy enterprise ATS still operating at large companies and government agencies. Notorious for clunky application forms and aggressive keyword filtering. Older Taleo instances struggle with PDF parsing — DOCX is safer.
KSA (Knowledge, Skills, Abilities)
The federal-resume framework. USAJOBS postings list specific KSAs (e.g., "knowledge of OMB Circular A-130," "skill in MS Project"); applicants must address each one with concrete examples. Failure to address a KSA is a knockout. See the federal resume guide.
OSHA 10 / OSHA 30
Mandatory construction-trades safety certifications. OSHA 10 is the entry-level card (10 hours of training); OSHA 30 is for supervisors and foremen. Many trades job boards (Roadtechs, Tradesmen International, IBEW locals) filter applicants without an active card. See the trades resume guide.
NCCER
National Center for Construction Education and Research credential. The portable trades certification recognized across most US construction employers. NCCER tracks training hours via a database that contractors verify before hiring.
Cover letter
A 200–400 word document explaining why you're applying to this specific role and why you're a fit. Most ATS will accept and parse a cover letter; most recruiters skim it only after your resume passes the keyword filter. Including the ATSHack tailor's cover-letter add-on costs $0.50.
Professional summary
The 2–4 sentence block at the top of a resume positioning your experience for a target role. Replaces the older "Objective" section. Heavily weighted by ATS keyword scans because it's the densest, highest-position text on the page. How to write one →
Action verb
A strong verb that opens a resume bullet — built, shipped, led, reduced, automated, owned. Replaces weak phrasing like "responsible for" or "helped with." ATS keyword scans pick up action verbs as signal of contribution. See 50 action verbs that get noticed.
STAR format
Situation, Task, Action, Result. The structure recruiters score behavioral interview answers on. Aim for 4–6 sentences per answer. The ATSHack Pro plan includes a STAR coach that grades your practice answers.