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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.