Glossary
Short, sourced definitions for the technical terms that show up across Convertitive’s tools and methodology pages. Each term has its own page with examples and a link back to the tool it’s used in.
- APR Finance
- Annual Percentage Rate. The yearly interest rate on a loan, inclusive of certain fees.
- APY Finance
- Annual Percentage Yield. Yearly return rate accounting for compounding.
- ASCII Code
- American Standard Code for Information Interchange. 7-bit character encoding for English text.
- Base64 Code
- A binary-to-text encoding using 64 ASCII characters. Standard for embedding binary data in text-only contexts.
- Bessel's correction Math
- Dividing by N−1 instead of N when computing sample variance, to remove sample-vs-population bias.
- BigInt Code
- JavaScript primitive for arbitrary-precision integer arithmetic.
- BMI Health
- Body Mass Index. The weight-to-height ratio used as a population-level screening metric.
- Chroma subsampling Image
- Storing colour at lower resolution than brightness, exploiting human vision's lower colour sensitivity.
- DEFLATE Code
- Lossless compression algorithm. The compression behind PNG, ZIP, gzip.
- Gas Mark Cooking
- British oven temperature scale. Mark 1 = 275°F = 135°C, then 25°F per mark.
- Gwei Crypto
- Ethereum's gas-price unit. 1 Gwei = 10⁻⁹ ETH = 10⁹ Wei.
- IANA timezone Date & time
- A canonical timezone identifier (like 'Europe/London') from the IANA Time Zone Database.
- ISO 8601 Date & time
- The international standard for representing dates and times. YYYY-MM-DDTHH:MM:SSZ.
- JWT Code
- JSON Web Token. Three base64url-encoded segments: header.payload.signature.
- Leap second Date & time
- One-second adjustment to UTC to keep atomic time aligned with Earth's rotation.
- Mid-market rate Currency
- The midpoint between buy and sell prices on the interbank currency market.
- MIME type Code
- Media type identifier telling a client what kind of data a payload contains.
- hreflang Web
- HTML attribute telling search engines which language and region a page targets.
- Mortgage Finance
- A long-term, secured loan used to buy real estate. Standard amortising-loan math.
- Planck constant Units
- Fundamental physical constant (6.62607015 × 10⁻³⁴ J·s) that defines the kilogram.
- SHA-256 Code
- Cryptographic hash function producing 256-bit digests. The modern standard.
- Unicode Code
- Universal character encoding standard covering every writing system in active use.
- UTF-8 Code
- Variable-width Unicode encoding using 1-4 bytes per character. ASCII-compatible.
- NIST Units
- US National Institute of Standards and Technology. Publishes the canonical reference for US units in SI.
- Percentile Math
- The value below which a given percentage of observations fall. 90th percentile = beats 90% of the data.
- Sample standard deviation Math
- Square root of variance, using Bessel's correction (divide by N−1) to correct for sample-vs-population bias.
- Satoshi Crypto
- The smallest unit of Bitcoin. 1 BTC = 100,000,000 satoshi.
- sRGB Color
- Standard RGB — the default colour space of the web and most consumer displays.
- UTC Date & time
- Coordinated Universal Time. The reference clock every IANA timezone offset is measured against.
- Wei Crypto
- The smallest, indivisible unit of Ether. 1 ETH = 10¹⁸ Wei.
- BMR Health
- Basal Metabolic Rate. The energy your body burns at complete rest.
- TDEE Health
- Total Daily Energy Expenditure. BMR × activity multiplier.
- Brannock device Sizes
- Metal foot-measuring tool used by US shoe stores since 1925.
- Mondopoint Sizes
- International shoe sizing system. Foot length in millimeters (ISO 9407).
- Interbank rate Currency
- The wholesale exchange rate at which large banks trade currencies with each other.
- GPT token AI
- The atomic unit of LLM input/output. ~4 English characters per token.
- LLM AI
- Large Language Model. Neural network trained to predict the next token.
- Context window AI
- Maximum tokens an LLM can process in a single inference (input + output combined).
- Naegele's rule Health
- Standard obstetric formula: estimated due date = LMP + 280 days.
- Heron's formula Math
- Compute triangle area from three side lengths without needing the height.
- Gamut Color
- The complete set of colours a colour space or device can represent.
- Display P3 Color
- Wide-gamut RGB colour space used by modern Apple displays. ~25% more colour volume than sRGB.
- Pantone Color
- Proprietary spot-colour matching system. Each Pantone number is an exact ink formulation.
- Kelvin Units
- The SI base unit of temperature. Absolute zero is 0 K (−273.15°C).
- DEXA Health
- Dual-energy X-ray absorptiometry. Clinical gold-standard scan for body composition.
- Fluid ounce Units
- Volume unit. 1 US fl oz = 29.5735 ml. 1 UK fl oz = 28.4131 ml.
- Decibel (dB) Units
- Logarithmic ratio unit. 10 dB = 10× power; 20 dB = 100× power.
- Hertz (Hz) Units
- The SI unit of frequency. One cycle per second.
- pH Science
- Logarithmic measure of acidity, 0-14. Each unit is 10× the hydrogen ion concentration.
- Density Science
- Mass per unit volume. Why a cup of feathers weighs much less than a cup of flour.
- Viscosity Science
- How resistant a fluid is to flow. Water is 1 cP; honey is 10,000.
- Maillard reaction Cooking
- Chemical browning of amino acids + sugars at high heat. The flavour behind seared meat.
- Autolyse Cooking
- A rest in bread dough mixing — flour + water only, before yeast and salt.
- ICC profile Color
- Standardised description of a colour device's behaviour. Makes cross-device colour reproducible.
- IEEE 754 Code
- The standard for floating-point arithmetic. Why 0.1 + 0.2 = 0.30000000000000004.
- Lossy compression Image
- Compression that discards information to save space. JPG, MP3, MP4.
- Lossless compression Image
- Compression that preserves every byte. PNG, FLAC, ZIP.
- bps Code
- Bits per second. Internet speeds, video bitrates. Different from Bps (bytes per second).
- Kibibyte (KiB) Code
- Exactly 1024 bytes. The unambiguous binary alternative to 'kilobyte'.
- BSON Code
- Binary JSON. MongoDB's native storage format with extended types.
- OTP Security
- One-Time Password. Single-use code, typically 6 digits. The 2FA building block.
- TOTP Security
- Time-based One-Time Password (RFC 6238). Authenticator-app code derived from a shared secret + 30-second window.
- CSRF Security
- Cross-Site Request Forgery. Attack where a malicious site triggers authenticated requests using the victim's cookies.
- XSS Security
- Cross-Site Scripting. Injection of attacker JavaScript into a victim's view of a trusted site.
- SAML Security
- Security Assertion Markup Language. XML-based SSO standard, dominant in enterprise.
- OAuth 2.0 Security
- Delegated authorization protocol. 'Allow this app to access my Google account without giving it my password.'
- CORS Web
- Cross-Origin Resource Sharing. Browser mechanism for controlled cross-origin requests.
- CSP Security
- Content Security Policy. HTTP header that whitelists allowed sources of scripts, styles, images.
- SRI Security
- Subresource Integrity. Pin a hash of an external script; refuse to run it if bytes don't match.
- ETag Web
- Entity Tag. HTTP cache-validation header containing a hash or version of the resource.
- Referer Web
- HTTP request header (famously misspelled) carrying the URL the user came from.
- User-Agent Web
- HTTP header identifying the client. Notoriously overgrown, lies about itself for backwards-compatibility.
- SVG Image
- Scalable Vector Graphics. XML-based vector image format. The right choice for logos and icons.
- WebP Image
- Modern web image format. Both lossy and lossless modes, full alpha, ~30% smaller than JPG at equivalent quality.
- AVIF Image
- AV1 Image File Format. ~20-30% smaller than WebP. Slow to encode, fast to decode.