Complete File Format Encyclopedia

Lossless compression reduces file size while preserving all original data. When decompressed, the file is identical to the original before compression. Examples include PNG for images, FLAC for audio, and ZIP for general files. Lossy compression permanently removes some data to achieve smaller file sizes. The degree of quality loss depends on the compression level. Examples include JPEG for images, MP3 for audio, and MP4 with H.264 for video. Lossy formats are typically much smaller but sacrifice some quality, while lossless formats preserve quality but result in larger files.

Files may not open in certain applications for several reasons: the application might not support that file format; the file could be corrupted or incomplete; the file might be using a newer version of the format than the application supports; or the file extension might not match the actual format of the file. To resolve this issue, try using a file conversion tool to convert to a compatible format, update your application to the latest version, or use an alternative application that supports the format. For proprietary formats, you may need specific software from the format’s developer.

For long-term archiving, choose formats that are widely supported, standardized, and less likely to become obsolete. For documents, consider PDF/A, a specialized version of PDF designed specifically for archival. For images, TIFF or DNG (for digital negatives) are good choices. For audio, uncompressed WAV or FLAC provide lossless quality. For video, consider MKV containers with broadly supported codecs or archival-specific formats like FFV1. Always prioritize open, documented formats over proprietary ones, and consider making multiple copies in different formats for critical data. Regularly migrate your archives to new formats as standards evolve.

You can convert between file formats using specialized conversion software, online conversion services, or built-in features in various applications. For document formats, Microsoft Office, LibreOffice, and Google Docs all provide export options to different formats. For images, tools like Adobe Photoshop, GIMP, and IrfanView offer conversion capabilities. For audio and video, applications like HandBrake, FFmpeg, and Audacity are powerful options. Many free online services also exist for simple conversions, though be cautious about uploading sensitive information. When converting, be aware that some conversions may result in quality loss or loss of features, especially when converting from a more capable format to a simpler one.

File corruption can occur for various reasons including improper shutdowns, hardware failures, software bugs, virus infections, interrupted transfers, or storage media degradation. To prevent file corruption, adopt these practices: always use the “safely remove” option for external drives; keep your operating system and applications updated; use antivirus software; avoid interrupting file operations like saving or copying; implement a regular backup strategy with multiple copies; use file verification tools that check data integrity; and consider using file systems with built-in error correction. If you have important files, regularly verify their integrity and migrate them to new storage media every few years.

Container formats (like MP4, MKV, AVI) are wrappers that hold multiple data streams such as video, audio, subtitles, and metadata in a single file. They define how these elements are organized but not how the actual content is encoded. Codecs (like H.264, VP9, AAC, MP3) are the technologies that encode and decode the actual audio or video data streams, determining the compression method and quality. A single container format can support multiple different codecs, and the same codec can be used in different container formats. Understanding this distinction helps when troubleshooting compatibility issues, as both the container and the codec must be supported by your playback device or software.