JPG compression uses lossy algorithms that reduce file size by removing imperceptible image data. A JPG compressor analyzes image complexity and applies variable compression rates across different areas. Modern JPG compression tools can reduce file sizes by 60-90% while maintaining excellent visual quality for photos and complex images.

Compressed JPG files load faster on websites, save storage space, and are easier to email or share. Large JPG files slow down page load times and consume bandwidth. Using a JPG compressor to shrink images can reduce file sizes by 70-90% with minimal visible quality loss, perfect for photography, web galleries, and social media.

Online JPG compression requires uploading photos to external servers, risking privacy and requiring internet. Offline JPG compressor tools like TinyFast compress images directly on your Mac - faster, more secure, and work without internet. Offline compression protects your private photos and uses hardware acceleration for instant results.

JPG is already a compressed format, but modern JPG compressors can reduce size further with minimal quality loss. Quality reduction depends on compression level - at 80-90% quality, most people can't see the difference. Smart JPG compression algorithms preserve important details while removing unnecessary data, achieving 50-80% size reduction with excellent visual results.

For web use, compress JPG at 80-85% quality for the best balance of size and appearance. For printing, use 90-95% quality. For social media, 70-80% is sufficient. Progressive JPG encoding improves perceived load speed. Always keep original files before compressing, and preview results before finalizing compression settings.