Glossary

Joint Photographic Experts Group. A lossy image format designed for photographs. JPG achieves small file sizes by discarding subtle color information the human eye doesn't easily notice. Quality ranges from 1-100 (or 0-1.0); typical web use is 72-85%. Once saved as JPG, the discarded data cannot be recovered - every re-save adds more loss. Best for photos, hero images, and social media. Not ideal for logos, text, or images with sharp edges.

Portable Network Graphics. A lossless image format - every pixel is stored exactly as-is. PNG supports full transparency (alpha channel), making it the go-to format for logos, UI elements, screenshots, and any image where pixel-perfect reproduction matters. PNG files are larger than JPG for photographs, but superior for graphics with text, solid colors, or transparency. Not designed for photographs where file size is a concern.

A modern image format developed by Google. WebP supports both lossy and lossless compression, as well as transparency and animation - making it a versatile replacement for both JPG and PNG. WebP files are typically 25-35% smaller than equivalent JPGs at the same visual quality. Supported in all modern browsers (Chrome, Firefox, Safari 14+, Edge). Not universally supported in all image editors and older software, which is why conversion tools are useful.

MPEG-4 Part 14. The most widely used video container format. An MP4 file is a container that holds video data (typically encoded with H.264 or H.265), audio data (typically AAC), and optional subtitles and metadata. MP4 strikes a balance between quality and file size, which is why it's the default format for smartphones, streaming services, and social media. MP4 files can also contain audio-only content by omitting the video track.

MPEG-1 Audio Layer III. The most universally compatible audio format in the world. MP3 achieves compression by removing frequencies that are masked by louder sounds (psychoacoustic modeling). Common bitrates: 128kbps (acceptable), 192kbps (good), 320kbps (near-lossless). MP3 is supported by every media player, phone, car stereo, and streaming platform. Its main drawback is that it's a lossy format - higher-quality recordings require higher bitrates.

Waveform Audio File Format. An uncompressed (or minimally compressed) audio format developed by Microsoft and IBM. WAV files store raw PCM audio data, meaning every sample is stored at full precision - no quality loss. This makes WAV the preferred format for audio editing, music production, and archiving. The downside: WAV files are large. A 3-minute song at CD quality (44.1kHz, 16-bit stereo) is about 30MB as WAV versus ~3-5MB as MP3.

The process of encoding data using fewer bits than the original representation. Two types exist: Lossless compression (PNG, ZIP, WAV with ADPCM) discards nothing - the original can be perfectly reconstructed. Lossy compression (JPG, MP3, WebP lossy) permanently discards data that's unlikely to be noticed - achieving much better compression ratios. For file tools, "compress" typically means applying or increasing lossy compression to reduce storage size.

The amount of data used to represent one second of audio or video, measured in kilobits per second (kbps) or megabits per second (Mbps). Higher bitrate = higher quality + larger file. For video: 1-5 Mbps (streaming), 8-15 Mbps (HD download), 50+ Mbps (professional). For audio: 128 kbps (acceptable), 192 kbps (good), 320 kbps (excellent). Bitrate directly controls the quality-vs-size tradeoff. KitDevs sets sensible defaults (192kbps for MP3, 128kbps for M4A) that work for most use cases.

A browser-native JavaScript API for drawing and manipulating graphics. KitDevs uses the OffscreenCanvas variant for image processing - it runs off the main thread, preventing the UI from freezing. The Canvas API can decode any image format the browser understands (JPG, PNG, WebP, GIF, AVIF) and re-encode it as a different format. This is how KitDevs achieves instant, private image conversion and compression without any server infrastructure.

A binary instruction format that allows code written in C, C++, Rust, and other languages to run in the browser at near-native speed. KitDevs uses FFmpeg compiled to WebAssembly for video/audio processing. This is the same FFmpeg used by professional tools like VLC and Handbrake - now running entirely in your browser tab. WebAssembly is supported in all modern browsers and does not require any browser plugins or extensions.

The fundamental tradeoff in data compression. Lossless: the original data can be perfectly reconstructed from the compressed version. Examples: PNG (images), ZIP (files), FLAC (audio). Lossy: some data is permanently discarded during compression - but the discarded data is chosen to be imperceptible. Examples: JPG, MP3, MP4 (H.264). Lossy compression achieves dramatically smaller file sizes at the cost of minor, usually invisible, quality reduction.