Here is a summary that appears, in some close variation, on an enormous number of resumes: "Results-driven professional with excellent communication and leadership skills, seeking to leverage experience to contribute to a dynamic organization." It is grammatically fine. It is also true of almost nobody and almost everybody at the same time, which means it tells the reader nothing. If you removed the name from the top of that resume, this sentence would fit on the next fifty resumes in the pile too.
A summary that works does three things in two or three sentences: says what you do, at what level, and what makes you specifically worth the next look. Below are real examples across different situations — steal the structure, not the words.
Early career / first professional role
The trap here is trying to sound senior. You are not senior yet, and pretending otherwise reads as unearned. Lean on what you actually have: relevant coursework, internships, projects, and speed of learning.
Weak: "Recent graduate eager to apply my skills in a challenging role."
Better: "Marketing graduate with two internships in social content and paid campaign support. Built and ran a 6-week Instagram campaign for a student org that grew followers by 3x on a $0 budget."
More on this specific situation in how to write a resume with no work experience.
Mid-career individual contributor
The goal is specificity about scope and outcome, not a list of adjectives.
Weak: "Experienced software engineer with strong problem-solving abilities and a passion for clean code."
Better: "Backend engineer with 5 years building payment infrastructure. Reduced checkout latency 60% by rearchitecting a legacy queue system; the fix is still running in production two years later."
Manager or team lead
At this level, the summary needs to show what you are responsible for producing through other people, not just your own output.
Weak: "Dynamic leader with proven ability to manage teams and drive results."
Better: "Operations manager leading a 14-person warehouse team across two shifts. Took over-budget fulfillment costs from 18% over target to on-budget within two quarters by rebuilding the shift-handoff process."
Career change
The summary is where you get ahead of the obvious question — why does your last job not match the one you're applying for — instead of hoping nobody asks it.
Weak: "Motivated individual transitioning into a new field, ready to learn."
Better: "Former high school teacher moving into instructional design. Ten years translating complex material into lessons that stick for a room of people with different starting points — the same skill instructional design asks for, applied to a different audience."
Full framework in how to write a resume for a career change.
Returning after a gap
You do not need to explain the gap in the summary — that belongs in a cover letter or interview if it comes up at all. The summary's job is to reestablish your current capability.
Weak: "Returning to the workforce after taking time off for family responsibilities."
Better: "Project manager with 8 years in construction scheduling, now returning to full-time work. Managed budgets and vendor contracts as a volunteer coordinator for a 200-person community organization during a career break."
The pattern across all of these
Every "better" version above does the same three things: a concrete role or scope, a specific outcome or proof point, and language that could only describe this one person's actual experience. If you can delete a sentence from your summary and put it on a coworker's resume without anyone noticing, it is not doing its job yet.
Write the honest, plain version first — what you actually did, in your own words — and tighten from there. The tightening is where craft matters. The honesty is where the substance comes from, and no amount of tightening fixes a summary with no substance underneath it.