Metadata
"Data about data". Images: EXIF (camera, GPS, timestamp). MP3: ID3 (artist, album). Filesystem: timestamps, permissions, owner. HTTP: headers (Content-Type, Cache-Control).
Standardized metadata formats: Dublin Core (libraries), Open Graph (social media preview), Schema.org (web SEO + LLM extraction), JSON-LD (linked data). Security risk: EXIF in photos can leak GPS location. Stripping tools: ExifTool. Modern web: <meta> tags for OG/Twitter Cards, JSON-LD in <script type="application/ld+json">. The metadata-in-filename pattern is primitive but works: vacation-2024-paris.jpg.