File formats
A file format defines how data is represented and interpreted. Choose one by the recipient's software, editing needs, fidelity and long-term access, not by extension alone.
File format basicsFormats
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FORMAT ATLAS
Formats
JPEGJPEG is a lossy image format used widely for distributing photographs.PNGPNG is a lossless raster image format that supports alpha transparency.PDFPDF is widely used to distribute and view documents while preserving their layout. It can hold multiple pages, text, images, and graphics.MP4MP4 is an MPEG-4 Part 14 container based on the ISO Base Media File Format. It can hold video and audio, but .mp4 alone does not identify codecs such as H.264, HEVC, AV1, or AAC.CSVCSV is a text format that represents tabular data with rows and delimiters. It suits simple table exchange but does not retain XLSX formulas, formatting, or multiple sheets.
Compare
JPEG vs PNGJPEG commonly uses lossy compression and suits many photographs, while PNG preserves pixel values losslessly and supports transparency. The choice depends on image content, editing needs, and the destination's requirements.MP4 vs WebMMP4 and WebM are containers for audio and video, not single codecs. MP4 is widely used across devices and services; WebM is a Matroska-based subset associated with web delivery. Size and quality depend on the encoded streams, settings, and playback environment.CSV vs XLSXCSV exchanges plain table values. XLSX is a spreadsheet file that can retain formulas, formatting, and multiple sheets.
Guides
Choose a photo file formatFor photographs, the best choice depends on whether you prioritize easy sharing, smaller web files, or production and editing requirements.Choose a video distribution formatChoose the container and the codecs inside it according to the playback destination and production workflow.Choosing a Data Exchange FormatStart with the receiving system's specification. Use JSON for structured API data, XML where an integration requires its schema, and CSV for a single table.
Related formats and reading
File extensionsAn extension such as .jpg or .pdf is a filename hint, not proof of the file's contents. Inspect the actual format before changing an extension or trusting a download.MIME typesA MIME type identifies the kind of content, often as type/subtype such as image/jpeg. It helps browsers and services handle files, but should be checked against the actual content.Container vs codecA container packages media streams, while a codec encodes audio or video inside it. MP4 or MKV alone does not tell you whether a device supports the internal codec.Metadata, sidecars and external dependenciesMetadata describes content or settings. Distinguish a separate sidecar from external data needed to load a file, and check where each item is stored.What checksums can and cannot verifyA hash is calculated from file bytes. Compare with a trusted expected value using the same algorithm, separately from content inspection and sender verification.