Frequently Asked Questions

A file extension is the suffix after the final period in a filename, such as .pdf, .jpg, or .docx. It tells operating systems and users which file type the name refers to, but it is not the same as the file format inside the bytes.

Search for the extension here first so you can see what it represents and which compatible applications can open it. Then download software from the publisher or a known official source and use that application to open the file.

No. Renaming photo.png to photo.jpg changes only the label. The image data remains PNG until a converter decodes it and writes a new file in the target format.

Not necessarily. Attackers can use uncommon or misleading extensions to disguise malicious files. Verify the source, scan the file, and never open executable formats such as EXE, BAT, or MSI from untrusted sources.

The reviewed dataset is updated weekly. Each record includes a reviewed date and source links so you can see when the information was last checked.

CRDOWNLOAD is a partial download marker used by Chromium browsers. It becomes the final filename only after the download completes; resume or restart the download instead of renaming the file.

No. A format is best only for a specific job. JPEG is efficient for photos but cannot hold transparency, while PNG keeps pixels lossless but makes photo files larger. The comparisons on this site explain the conditions under which one format beats another.

Lossy compression permanently removes data that is hard for humans to notice. It creates much smaller files for photos, audio, and video, but quality drops when the file is compressed again. Lossless compression, by contrast, keeps every original bit and only reduces redundancy.

Each verdict starts from the recorded attributes of the two formats, such as compression, transparency, animation, openness, and browser support. Rules score those attributes for a use case, and editorial notes add the practical conditions that a score alone cannot capture.

Format specifications and browser support claims are reviewed on a schedule, and every record shows a reviewed date and source links. Browser support and tooling change faster than the formats themselves, so review dates let you judge freshness at a glance.

A field is only shown when it makes sense for that format family. For example, transparency is not a meaningful attribute of an archive format, so the comparison omits it or marks it not applicable rather than guessing a value.

Yes. Use the contact page to send the page URL and the correction. We check every suggestion against official specifications or authoritative documentation before updating the record.