An action verb is the first word of a resume bullet — and it does more work than any other word on the page. "Led," "launched," "reduced," "shipped," "negotiated," "architected" all convey specific, active ownership. Weak openers — "Responsible for," "Helped with," "Worked on" — suggest you were present rather than responsible.
Match the verb to the scope and nature of the work. "Led" for people leadership; "Architected" or "Designed" for systems work; "Grew," "Drove," or "Generated" for revenue or growth; "Reduced" or "Cut" for cost or time savings. Avoid overused verbs ("Utilized," "Leveraged," "Assisted") and vary them across bullets so the resume doesn't read as formulaic.
Pair every action verb with a quantified outcome. "Led a team" is weak; "Led a 6-engineer team to ship v2 three weeks ahead of schedule, cutting onboarding time 42%" is a full, recruiter-ready bullet.