A resume on its way to a recruiter
You spent the afternoon polishing your resume in Word. The recruiter's job posting is explicit: "Send your resume as a PDF." You don't want to download a desktop tool, sign up for a service, or upload your work history to a stranger's server.
You drop the .docx into the converter, leave the page size on A4, and click Convert. A few seconds later you have a your-name.pdf in your Downloads folder. The headings, the bullet points, the tasteful horizontal rule between sections — all intact.
You attach the PDF to your application, hit send, and move on with your day. The recruiter opens it on her phone the next morning without knowing or caring how it got there.