Guides
Practical, jargon-light explainers that go with our tools. No fluff, no sign-up.
How to create a strong password (and why length beats symbols)
What actually makes a password hard to crack, why a long passphrase beats a short jumble of symbols, and how to manage credentials without losing your mind.
Updated June 2026JSON vs YAML: which should you use, and when?
The real differences between JSON and YAML — readability, comments, data types and footguns — and a simple rule of thumb for choosing between them.
Updated June 2026BMI explained: what it measures, and what it misses
Where the Body Mass Index formula comes from, how to read your number, and why it is a screening signal rather than a verdict on your health.
Updated June 2026How to calculate percentages: the three types explained
The three percentage questions you actually run into — "X% of Y", "X is what % of Y", and percent change — with the formulas and worked examples.
Updated June 2026Compound interest explained (with the formula)
Why compounding beats simple interest, how compounding frequency and regular contributions change the outcome, and the rule of 72.
Updated June 2026How many calories should you eat? BMR vs TDEE
How your resting burn (BMR) and activity combine into daily calories (TDEE), and how a sensible deficit or surplus maps to weight change.
Updated June 2026Body fat percentage: methods and healthy ranges
Why body-fat percentage can beat BMI, how the common measurement methods compare, and the healthy ranges for men and women.
Updated June 2026Hashing explained: MD5, SHA-256 and why salting matters
What a cryptographic hash is, why MD5 and SHA-1 are no longer safe, and how salting plus slow algorithms protect stored passwords.
Updated June 2026What is Base64 encoding (and when to use it)
How Base64 turns binary into text, why it is encoding and not encryption, the URL-safe variant, and where it actually shows up.
Updated June 2026Regular expressions: a beginner’s guide
The metacharacters, quantifiers, anchors and groups that make up a regex — explained with patterns you can try right away.
Updated June 2026Understanding JSON Web Tokens (JWT)
The three parts of a JWT, what the standard claims mean, how the signature works, and why you must never put secrets in the payload.
Updated June 2026HEX, RGB and HSL: understanding colour codes
How the three common ways to write a colour relate, when HSL is easier to work with, and how contrast affects accessibility.
Updated June 2026How to calculate and use running pace
Pace versus speed, how to work out your pace for any distance, and how to use it to plan even or negative race splits.
Updated June 2026