File extensions
An 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.
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.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.
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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.Choosing a Spreadsheet Exchange FormatUse CSV to exchange values in a single table. Choose XLSX when the recipient needs formulas, formatting, or multiple worksheets.
Related formats and reading
File formatsA 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.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.