Knowledge base
Short, sourced explanations of the formats, codes and numbers you meet every day. Each article answers the question first, then explains why, with links to the standards and to a free tool that runs in your browser.
Images and files
- 3 min readWhat is HEIC?iPhone photo format, how it differs from JPG, and when to convert.
- 4 min readJPG vs PNG vs WebP vs AVIFWhich image format to use for photos, screenshots and the web.
- 4 min readWhat is EXIF data?Camera, time and GPS details hidden in photos, and how to remove them.
- 4 min readDPI vs PPIPixels, print size and why 300 DPI only matters on paper.
- 3 min readAspect ratios explained16:9, 4:3, 1:1, 9:16 and the pixel sizes that go with them.
- 4 min readWhy are PDF files so large?Images, fonts and scans that bloat a PDF, and what compression changes.
Text, data and security
- 3 min readWhat is Base64?How Base64 turns bytes into text, why it grows 33%, and why it is not encryption.
- 4 min readUnicode and UTF-8Code points, bytes, and why text turns into garbled characters.
- 4 min readURL encoding (percent-encoding)Why spaces become %20 and which characters must be escaped.
- 4 min readJSON vs YAML vs XMLSyntax, strengths and pitfalls of the three data formats.
- 4 min readMD5 vs SHA-256What a hash is, which ones are broken, and what to use for passwords.
- 4 min readWhat makes a password strong?Length, randomness and entropy, following current NIST guidance.
- 4 min readWhat is a UUID?UUID versions 4 and 7, collision odds and when to use each.
Dates and time
Money math
Tutorials on cv.cm show how to get a job done. These articles explain what is going on underneath: why a photo is HEIC, why a PDF is 40 MB, why a password with four random words beats one with symbols.
Every article is checked against the published standard or official documentation listed under Sources, and dated so you can see when it was last reviewed.
FAQ
Who writes these articles?
The cv.cm team writes them and checks each fact against the standards and official documentation listed at the end of every article.
Can I use the tools mentioned here for free?
Yes. The linked tools are free, need no account and process files in your browser.
How is a knowledge article different from a tutorial?
A tutorial walks through one task step by step. A knowledge article explains the idea behind it, such as how a format or a formula works, so you can make your own decisions.