Find out what media extensions mean, when to use each format, and why codecs, compression and software compatibility matter.
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Note: a filename extension is a clue, not proof of a file's actual contents. Software support can vary by codec, version, browser, operating system and installed components.
What is a media file format?
A file format describes how digital information is arranged and interpreted. A filename extension—the letters after the last dot, such as .png or .mp4—often hints at that format. It does not guarantee what is inside the file: an extension may be renamed, reused by unrelated applications or paired with several internal encodings.
Images primarily store visual information, videos store moving pictures and often audio, and editing projects keep instructions, layers or references needed to make finished content. A finished video and its editing project are not interchangeable.
Why containers and codecs are different
A container such as MP4, MKV or MOV packages video, audio, subtitles and metadata. A codec such as H.264, HEVC or AV1 compresses or decompresses the actual video. Two MP4 files can use different codecs and therefore play differently on the same device.
Which image format should you choose?
Start with the intended use: is the image a photograph, a graphic with crisp text, a logo that must scale, a transparent overlay or an editable design?
Task
Good starting choice
Why
Sharing photos
JPEG or WebP
Broad compatibility or smaller web delivery.
Screenshots with small text
PNG
Lossless edges and crisp type.
Website images
WebP or AVIF, with fallback where appropriate
Efficient compression; test actual browser support.
Logos and icons
SVG, if the artwork is vector
Scales without raster pixelation.
Animated graphics
Animated WebP, APNG or GIF
Choose based on transparency, colors and target support.
Print and professional scans
TIFF or source application's format
Flexible high-quality workflows.
Photo editing from a camera
Original RAW file
Retains more capture data for processing.
There is no universally best format. Dimensions, image content, compression settings and device support matter as much as the extension.
Which video format should you choose?
For general online sharing, an MP4 container with H.264 video and AAC audio is a widely compatible starting point. For web delivery, WebM with VP9 or AV1 may offer alternatives. For editing, your production pipeline may prefer MOV or MXF with edit-friendly codecs.
Format
Typical strengths
Watch out for
MP4
Very common distribution container
Not every codec inside is universally supported.
WebM
Open, browser-focused delivery
Compatibility with some editing apps may vary.
MOV
Flexible professional editing workflows
Large sizes or unsupported internal codecs.
MKV
Multiple tracks, subtitles and metadata
Some televisions and devices have limited support.
AVI / WMV / FLV
Compatibility with older collections
Legacy codec and playback concerns.
Resolution, frame rate and bitrate
Resolution measures frame dimensions (such as 1920 × 1080), frame rate measures frames per second, and bitrate describes how much encoded data is used over time. High settings can improve fidelity but increase file size; the right balance depends on movement, detail and compression efficiency.
Lossy vs lossless compression, transparency and HDR
Lossy compression discards some information to reduce size; this is typical for JPEG and many delivery-video codecs. Lossless compression preserves the decoded information and is useful for screenshots, graphics and archives. Lossless does not always mean a visually better result—it depends on the source and settings.
Transparency allows parts of an image to show whatever is behind it. PNG, WebP, AVIF and SVG can support transparency, while conventional JPEG cannot. HDR allows an extended brightness or color range in compatible workflows. A format's support for HDR does not mean every app or display will present it correctly.
What does a RAW photo mean?
Camera RAW files usually preserve sensor-oriented capture data and processing metadata. They are useful for exposure and color work, but often require dedicated software. Different camera makers use different extensions, and not every editor supports every camera model immediately.
How to open, convert and check media files safely
Identify the file: check its extension, source and size. If it came from an unknown sender, do not assume a familiar extension makes it safe.
Use a compatible application: a media inspector can show the actual container, streams and codecs when a file will not play.
Convert a copy: keep the original before transcoding or re-encoding. Some conversions lose quality, layers, metadata or transparency.
Export for the audience: choose settings appropriate to the intended browser, phone, editor or television, then test the output.
Check project dependencies: editing project files may refer to external footage, fonts, LUTs or plugins. Copying the project alone may not be enough.
For images, copying pixels into a new format is not always equivalent to preserving layers or editing history. For video, rewrapping changes the container without necessarily re-encoding the streams; transcoding changes the encoded streams and can affect quality.
Media format terminology: quick glossary
Raster vs vector
Raster images are grids of pixels; vectors describe paths and shapes. Raster photos and vector logos serve different needs.
Alpha channel
Extra image information that can control how transparent a pixel appears.
Chroma subsampling
A video or image technique that reduces color-detail data relative to brightness information.
Metadata
Information stored alongside media, such as dimensions, capture settings, timestamps or author details.
Variable frame rate
Video timing where the number of frames per second can change throughout playback.
Container vs elementary stream
A container packages tracks and metadata; an elementary stream stores a codec's encoded content without that full packaging.
Frequently asked questions
Is JPG the same as JPEG?
Yes. .jpg and .jpeg typically name the same JPEG image format; the shorter suffix remains common for historical reasons.
Is PNG better than JPG?
PNG is useful for lossless graphics and transparency; JPEG is frequently smaller for photographs. Neither is best for every task.
Is WebP better than PNG or JPEG?
WebP can be efficient for many web images and supports both lossy and lossless compression. Visual quality, compatibility and encoding settings should guide your choice.
What is the difference between MP4 and H.264?
MP4 is a container. H.264 is a video codec that can be stored inside MP4 and other containers.
Why won't my MP4 video play?
The video or audio codec inside the container may not be supported by your player. A damaged file can also cause playback failure.
Does changing .heic to .jpg convert an image?
No. Renaming the extension changes the filename but does not convert the underlying image data.
What is the best format for social media uploads?
Follow the platform's current media recommendations. JPEG, PNG and MP4 are common starting points, but accepted codecs and sizes vary.
Can SVG files be unsafe?
SVG is XML-based and can contain active content or references. Treat unexpected SVG files with care, especially when opening them in software that supports active features.
Are editing project files the same as exported videos?
No. Projects such as .prproj and .aep store editing instructions or linked assets; exported videos are finished media files.
Does this directory prove what an unknown file contains?
No. It explains common meanings of extensions. Some suffixes are ambiguous or misnamed, and checking the file's actual structure may be necessary.