PDF compression uses multiple strategies: structural optimization removes redundant data, image compression reduces embedded photos, and object stream compression optimizes internal PDF structures. Modern PDF compressor tools can reduce file sizes by 30-90% depending on content type - image-heavy PDFs compress more than text-only documents.

Compressed PDF files are easier to email, faster to download, and use less storage space. Many email providers have 25MB attachment limits. Using a PDF compressor to reduce file size ensures documents can be shared easily, load faster on websites, and save cloud storage costs while maintaining readability.

Online PDF compression requires uploading sensitive documents to external servers, risking privacy and security. Offline PDF compressor tools like TinyFast compress PDFs directly on your Mac - faster, completely private, and work without internet. Your confidential documents never leave your device, ensuring data security and GDPR compliance.

It depends on the compression method. Lossless PDF compression reduces file size by 5-15% without any quality loss - perfect for text documents. Balanced compression achieves 30-70% reduction with minimal visible quality impact. Maximum compression can reduce files by 60-90% with some quality trade-off, ideal for scanned documents where perfect quality isn't critical.

For contracts and legal documents, use lossless compression to preserve quality. For presentations and reports, balanced compression (70% quality) offers optimal size reduction with excellent quality. For large scanned documents and archives, maximum compression (50% quality) provides dramatic size reduction. Always preview compressed PDFs before sharing important documents.