Output, Export, and File Formats
Formats and their roles
Know the core formats: PSD (layered working file), PSB (large document), TIFF (lossless, print, layers optional), JPEG (lossy, no transparency), PNG (lossless, transparency, web), GIF (indexed, limited colors, animation), PDF (print and presentation), and WebP (modern web). Understand that JPEG discards data and cannot store alpha transparency, while PNG-24 preserves it.
Export workflow
Use Save As for layered formats, Export As for web formats with quality and scale controls, and Export > Save for Web (Legacy) for optimized web output. Artboards allow multiple layouts in one document and export individually. Understand generator and Export As presets conceptually.
Print output
Know print resolution (typically 300 ppi for photos), bleed and crop marks, color separation in CMYK, and soft proofing with a printer profile. Understand that flattening removes layers and transparency, and that some print pipelines require flattening.
Worked rule of thumb
Ask "is transparency needed?" - if yes, PNG or TIFF; if no and file size matters, JPEG. Ask "must layers survive?" - if yes, PSD, TIFF, or PDF; if no, flatten and export.
Traps
Saving a JPEG from a transparent document fills transparency with white (or the matte color). Resizing on export changes pixel dimensions, not the saved document. CMYK files may shift color on screen compared to RGB.