File Format Glossary
50+ file format terms explained clearly — image, video, audio, and PDF formats, codecs, compression concepts, and technical specs.
Image Concepts
All Terms — A to Z
A
AACAAC is a modern audio codec used by Apple, YouTube, and streaming services. Learn about AAC vs MP3 quality, bitrate recommendations, and device support.Alpha ChannelAlpha channel is the transparency layer in image formats. Learn what alpha channel means, which formats support it (PNG, WebP, not JPEG), and how it works.Aspect RatioAspect ratio is the proportional relationship between image width and height. Learn common aspect ratios (16:9, 4:3, 1:1) and how they affect cropping and display.Audio BitrateAudio bitrate measures data per second of audio. Learn about CBR vs VBR, recommended bitrates (128, 192, 320 kbps), and how bitrate affects audio quality.AVIAVI is a legacy Microsoft video container format. Learn about AVI vs MP4, codec support, file size issues, and how to convert AVI to modern formats.AVIFAVIF is a next-generation image format based on the AV1 codec. Up to 50% smaller than JPEG. Learn about AVIF browser support, conversion, and use cases.
B
Bit DepthBit depth controls how many colors an image can contain. Learn about 8-bit vs 16-bit images, HDR, and when higher bit depth matters.Bitrate (Video)Video bitrate is the amount of data used per second of video. Learn about CBR vs VBR, recommended bitrates for different resolutions, and how bitrate affects quality.BMPBMP is an uncompressed bitmap image format native to Windows. Learn about BMP file size, when to use it, and how to convert BMP to JPG or PNG.
C
CodecA codec is an algorithm that compresses and decompresses video or audio. Learn about H.264, H.265, VP9, AV1, MP3, AAC codecs and how they work.Color SpaceColor space defines the range of colors an image can contain. Learn about sRGB vs Adobe RGB vs Display P3, ICC profiles, and which color space to use for web and print.
F
FLACFLAC is a lossless audio format that preserves perfect CD quality while reducing file size by 40-60%. Learn about FLAC vs MP3, device support, and when to use FLAC.Flatten PDFFlattening a PDF merges all layers, form fields, and transparency into a single flat layer. Learn when and how to flatten a PDF, and which tools to use.Frame RateFrame rate (FPS) is the number of video frames per second. Learn about 24fps, 30fps, 60fps, how frame rate affects file size, and the right FPS for different uses.
H
H.264H.264 (AVC) is the most widely used video codec. Learn about H.264 quality settings, CRF values, bitrate, and why it's the default choice for video sharing.H.265H.265 (HEVC) is 40% more efficient than H.264 at the same quality. Learn about H.265 compatibility, hardware support, 4K encoding, and when to use H.265 vs H.264.HEICHEIC is Apple's default photo format since iOS 11. Learn what HEIC is, why iPhones use it, compatibility issues, and how to convert HEIC to JPG.
L
Linearized PDFA linearized PDF (fast web view) loads page-by-page for faster online viewing. Learn how PDF linearization works and how to create linearized PDFs.Lossless CompressionLossless compression reduces file size without any quality loss. Learn which image formats use lossless compression (PNG, WebP lossless, FLAC, ZIP) and how it works.Lossy CompressionLossy compression permanently removes data to achieve smaller file sizes. Learn how lossy compression works in JPEG, MP3, and how quality settings affect the trade-off.
M
MKVMKV is an open-source video container that supports multiple audio tracks, subtitles, and any codec. Learn about MKV vs MP4 and when to use each.Mono vs StereoMono audio uses one channel, stereo uses two. Learn when to use mono vs stereo, the file size difference, and how channel count affects audio quality.MOVMOV is Apple's QuickTime video container format. Learn about MOV vs MP4 compatibility, iPhone video format, and how to convert MOV to MP4.MP3MP3 is the most widely supported audio format. Learn about MP3 bitrates (128, 192, 320kbps), quality vs file size, and when to use MP3 vs AAC or FLAC.MP4MP4 is the most popular video container format. Learn about MP4 structure, codecs (H.264, H.265), compatibility, and when to use MP4 vs other formats.
O
OCROCR (Optical Character Recognition) converts scanned images and PDFs into searchable, editable text. Learn how OCR works and the best OCR tools.OGGOGG Vorbis is a free, open-source audio format comparable to MP3. Learn about OGG quality, compatibility, and when to use OGG vs MP3 or AAC.OpusOpus is a modern audio codec optimized for voice and music at low bitrates. Used by Discord, WhatsApp, and WebRTC. Learn about Opus quality and compatibility.
P
PDFPDF (Portable Document Format) is Adobe's universal document format. Learn about PDF structure, versions, compression, and the best PDF tools.PDF MetadataPDF metadata includes author name, creation date, software used, and XMP data. Learn about PDF metadata, privacy concerns, and how to remove or edit it.PDF/APDF/A is an ISO standard for long-term archival of PDF documents. Learn what PDF/A requires, the different versions (PDF/A-1, A-2, A-3), and when to use it.PDF/XPDF/X is an ISO standard for print production-ready PDFs. Learn about PDF/X-1a, X-3, and X-4 standards and what they require for professional printing.PNGPNG (Portable Network Graphics) is a lossless image format with transparency support. Learn when to use PNG vs JPEG, file size differences, and best use cases.PPIPPI (Pixels Per Inch) measures digital image resolution. Learn the difference between PPI and DPI, screen PPI values, and how PPI affects image quality.
R
RAWRAW is an unprocessed camera image format containing all sensor data. Learn about RAW files, why photographers use them, and how to convert RAW to JPEG.ResolutionImage resolution explained: pixel dimensions, DPI, print size, and screen resolution. Learn how resolution affects image quality for web and print.
S
Sample RateSample rate is the number of audio samples per second. Learn about 44.1kHz, 48kHz, 96kHz, the Nyquist theorem, and which sample rate to use for different applications.SVGSVG (Scalable Vector Graphics) is an XML-based vector image format that scales to any size without quality loss. Learn about SVG use cases, advantages, and limitations.
W
WAVWAV is Microsoft's uncompressed audio format. Learn about WAV file size, quality, when to use WAV for recording and editing, and how to convert WAV to MP3.WebMWebM is an open-source video format for web streaming. Learn about WebM vs MP4, codec support (VP8, VP9, AV1), and browser compatibility.WebPWebP is Google's modern image format that's 25-35% smaller than JPEG at the same quality. Learn about WebP support, conversion, and when to use it.