Prepress
Everything done to artwork after design and before press: color, bleed, resolution, fonts, proofs. The handoff, not the design.
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What it is
Prepress is everything between 'the design looks finished' and 'ink touches paper': converting color to the right CMYK or spot setup, adding bleed, checking image resolution, embedding or outlining fonts, setting trapping and overprints, imposing pages onto press sheets, and running a proof. Historically it was a whole department with cameras, film, and stripping tables. Today it is mostly software plus one very opinionated human at the print shop.
Reach for the word when you want to talk about the whole handoff rather than one check. Preflight is the automated scan inside prepress; prepress is the scan plus every fix that follows it. Most shops publish a spec sheet (bleed amount, PDF/X flavor, minimum PPI, total ink limit) and that sheet is the actual contract.
Gotcha: a printer's prepress team will happily 'fix' your file without asking, and their fix can flatten transparency, substitute a font, or convert your careful spot color to process. Ask for a proof after their corrections, not before, and get the last-minute changes in writing.
Ask AI for it
Act as a prepress technician and prepare this artwork for commercial offset printing. Convert all color to CMYK using the printer's output profile (keep any named Pantone spot inks as spot separations) and add 3mm bleed on every edge. Add trim and registration marks only if the printer's specification asks for them, since many shops want a marks-free PDF/X. Verify all placed images are 300 PPI or higher at final size, embed or outline every font, flag total ink coverage above the printer's published limit, and export as PDF/X-4. List every issue you found and what you changed.