Glossary

Clear, plain-English explanations of the terms behind our tools — SEO, finance, health and technology — each with links to the free tools that put the concept to work.

SEO & Web

301 Redirect

A 301 redirect permanently forwards one URL to another, passing most of the original page’s SEO value to the new address.

Alt Text

Alt text is a written description of an image in HTML that screen readers announce and search engines use to understand the image.

Anchor Text

Anchor text is the visible, clickable text of a hyperlink, which gives users and search engines context about the linked page.

Backlink

A backlink is a link from one website to another; search engines treat quality backlinks as votes of confidence that boost rankings.

Canonical URL

A canonical URL tells search engines which version of a page is the "master" copy when the same content is reachable at multiple addresses.

Core Web Vitals

Core Web Vitals are Google’s three user-experience metrics — LCP, INP and CLS — measuring loading speed, interactivity and visual stability.

Crawl Budget

Crawl budget is the number of pages a search engine will crawl on a site within a given timeframe, shaped by server capacity and page value.

Domain Authority

Domain authority is a third-party score (0–100) estimating how likely a website is to rank, based mainly on its backlink profile.

Featured Snippet

A featured snippet is a highlighted answer box at the top of Google results that quotes a page directly, often called "position zero".

HTTP Status Code

HTTP status codes are three-digit server responses (like 200, 301, 404, 500) indicating how a request for a web page was handled.

Keyword Density

Keyword density is the percentage of times a keyword appears in a text relative to the total word count.

Meta Description

A meta description is an HTML attribute that summarizes a page’s content, shown as the snippet under the title in search engine results.

Noindex

Noindex is a directive that tells search engines not to include a page in their search results.

Robots.txt

Robots.txt is a text file at a site’s root that tells search engine crawlers which parts of the site they may or may not crawl.

SERP (Search Engine Results Page)

A SERP is the page a search engine shows in response to a query, containing organic results, ads and special features like featured snippets.

Structured Data (Schema Markup)

Structured data is standardized code (usually JSON-LD using Schema.org vocabulary) that helps search engines understand page content and enables rich results.

Title Tag

A title tag is the HTML element that defines a page’s title, displayed as the clickable headline in search results and browser tabs.

XML Sitemap

An XML sitemap is a machine-readable file listing a site’s important URLs so search engines can discover and crawl them efficiently.

Finance

Amortization

Amortization is the process of paying off a loan through fixed regular payments that cover both interest and principal over time.

APR (Annual Percentage Rate)

APR is the yearly cost of borrowing money, including interest and standard fees, expressed as a percentage — without compounding effects.

APY (Annual Percentage Yield)

APY is the real yearly return on savings or investments including compound interest, making it higher than the nominal rate.

Compound Interest

Compound interest is interest earned on both the original amount and previously accumulated interest, producing exponential growth over time.

Gross vs. Net Income

Gross income is earnings before deductions; net income is what remains after taxes and other withholdings — your take-home pay.

Inflation

Inflation is the rate at which prices rise over time, reducing the purchasing power of money.

Net Worth

Net worth is everything you own (assets) minus everything you owe (liabilities) — the standard single-number snapshot of financial health.

Principal

Principal is the original amount of money borrowed, invested or saved, before any interest or returns are added.

ROI (Return on Investment)

ROI measures the profitability of an investment as a percentage: (gain − cost) ÷ cost × 100.

Health & Fitness

BMI (Body Mass Index)

BMI is a screening number relating weight to height (kg/m²); 18.5–24.9 is considered the healthy range for most adults.

BMR (Basal Metabolic Rate)

BMR is the number of calories your body burns at complete rest to maintain vital functions like breathing and circulation.

Body Fat Percentage

Body fat percentage is the share of your total weight that is fat tissue — a more direct measure of body composition than BMI.

Calorie

A calorie is a unit of energy; food "calories" are actually kilocalories (kcal), the energy needed to heat 1 kg of water by 1°C.

Macronutrients

Macronutrients are the three nutrients the body needs in large amounts — protein, carbohydrates and fat — which supply all dietary energy.

TDEE (Total Daily Energy Expenditure)

TDEE is the total calories you burn per day — your BMR multiplied by an activity factor — and the baseline for weight goals.