Business & Coding Dictionary

A step-by-step set of instructions to solve a specific problem. Think of it like a recipe — follow the steps and you get the result.

Example: A sorting algorithm arranges a list of numbers from smallest to largest.

A set of rules that lets different software applications communicate with each other. APIs define how to request and send data between systems.

Example: A weather app uses an API to fetch forecast data from a weather service.

A data structure that stores multiple values in a single variable, accessed by their position (index). Most arrays start counting from 0.

Example: colors = ['red', 'blue', 'green'] — colors[0] is 'red'.

A data type with only two possible values: true or false. Named after mathematician George Boole.

Example: isLoggedIn = true

An error or flaw in code that causes unexpected behaviour. The term dates back to an actual moth found in a computer in 1947.

A temporary storage layer that saves frequently accessed data so it can be retrieved faster next time, reducing load times.

Example: Your browser caches images so websites load faster on repeat visits.

A blueprint for creating objects in object-oriented programming. It defines properties (data) and methods (actions) that objects of that type will have.

Example: A 'Car' class might have properties like colour and speed, and methods like drive() and brake().

A tool that translates your entire source code into machine code before the program runs. Languages like C++ and Java use compilers.

Stands for Create, Read, Update, Delete — the four basic operations you can perform on data. Almost every app uses CRUD.

Example: A to-do app lets you create tasks, read the list, update items, and delete completed ones.

An organised collection of data stored electronically. Databases allow you to efficiently store, retrieve, and manipulate large amounts of information.

Example: A social media app stores user profiles, posts, and comments in a database.

The process of finding and fixing errors (bugs) in your code. It involves reading error messages, testing assumptions, and tracing through logic.

An external package or library that your project relies on to function. Managing dependencies is a key part of modern development.

Example: A React project depends on the 'react' and 'react-dom' packages.

A pre-built structure of code that provides a foundation for building applications. It gives you tools, patterns, and conventions to follow.

Example: React is a frontend framework. Django is a backend framework.

A reusable block of code that performs a specific task. Functions accept inputs (parameters), process them, and can return outputs.

Example: function add(a, b) { return a + b; }

A version control system that tracks changes to your code over time. It lets multiple developers collaborate and revert to previous versions if needed.

A software application that provides tools for writing, testing, and debugging code all in one place.

Example: VS Code, IntelliJ IDEA, and PyCharm are popular IDEs.

A lightweight data format used to store and exchange data. It's human-readable and widely used in APIs and configuration files.

Example: { "name": "Alice", "age": 25 }

A collection of pre-written code that you can use in your projects to avoid reinventing the wheel. Smaller and more focused than a framework.

Example: Lodash is a JavaScript utility library. NumPy is a Python math library.

A control structure that repeats a block of code multiple times until a condition is met. Common types include for loops and while loops.

Example: for (let i = 0; i < 5; i++) { console.log(i); }

A data structure that groups related data (properties) and actions (methods) together. Objects model real-world entities in code.

Example: let car = { brand: "Toyota", speed: 120, drive: function() {...} }

When a function calls itself to solve a problem by breaking it into smaller sub-problems. Requires a base case to stop the loop.

Example: Calculating factorial: factorial(5) = 5 × factorial(4) × ... × 1

A storage location for your project's code and its entire version history. Usually hosted on platforms like GitHub or GitLab.

A style of API design that uses standard HTTP methods (GET, POST, PUT, DELETE) to interact with resources. The most common API pattern on the web.

A named container that stores a value in memory. The value can change during the program's execution.

Example: let score = 0; score = score + 10;

The server-side part of an application that handles data processing, business logic, databases, and authentication. Users don't see it directly.

Example: When you log in, the backend checks your password against the database.

A language used to style and layout web pages. CSS controls colours, fonts, spacing, animations, and responsive design.

A tree-like representation of a web page that browsers create from HTML. JavaScript can manipulate the DOM to change what users see.

The client-side part of an application — everything the user sees and interacts with in their browser. Built with HTML, CSS, and JavaScript.

A developer who works on both the frontend and backend of an application. Full-stack developers can build complete applications independently.

The standard language for creating web pages. HTML defines the structure and content of a page using tags and elements.

The protocol used to transfer data on the web. HTTPS is the secure version that encrypts data in transit to protect users.

A design approach that makes web pages look good on all screen sizes — from mobile phones to desktop monitors — using flexible layouts and media queries.

A web app that loads a single HTML page and dynamically updates content without full page reloads, creating a smoother user experience.

Example: Gmail, Twitter, and Trello are SPAs.

A project management methodology that breaks work into small, iterative cycles (sprints). Teams deliver working software frequently and adapt to feedback.

The total cost of acquiring a new customer, including marketing, sales, and advertising expenses divided by the number of customers gained.

Example: If you spend £1,000 on ads and get 50 customers, your CAC is £20.

The percentage of customers who stop using your product or cancel their subscription within a given time period. Lower is better.

Example: If 100 users start the month and 5 cancel, your churn rate is 5%.

Automated processes that test your code when you push changes (CI) and automatically deploy it to production (CD). Essential for modern teams.

The amount an advertiser pays each time someone clicks their ad. A key metric in paid advertising.

Example: If your CPC is £0.50, each click on your ad costs fifty pence.

The cost an advertiser pays per 1,000 ad impressions (views). Used to measure ad campaign costs.

Example: A CPM of £5 means you pay £5 for every 1,000 times your ad is shown.

The percentage of people who click on a link or ad compared to the number who see it. Higher CTR means more engaging content.

Example: 1,000 impressions with 30 clicks = 3% CTR.

The process of making your application available to users by publishing it to a server or hosting platform.

A culture and set of practices that combines software development (Dev) and IT operations (Ops) to deliver software faster and more reliably.

The total revenue a business expects from a single customer over the entire duration of their relationship.

Example: A customer who pays £10/month and stays for 2 years has an LTV of £240.

The predictable monthly income a subscription business earns. A critical metric for SaaS companies.

Example: 500 customers × £20/month = £10,000 MRR.

The simplest version of a product that still delivers value to users. Built quickly to test an idea before investing heavily.

Example: A basic landing page with a sign-up form can validate demand before building a full product.

Software whose source code is freely available for anyone to view, modify, and distribute. Community-driven development.

Example: Linux, React, and Python are all open-source projects.

The revenue earned per 1,000 page views or ad impressions. A key metric for content creators and publishers.

Example: An RPM of £8 means you earn £8 for every 1,000 page views.

A software distribution model where applications are hosted in the cloud and accessed via subscription rather than purchased outright.

Example: Netflix, Slack, and Notion are SaaS products.

An Agile framework that organises work into time-boxed sprints (usually 2 weeks). Teams have daily standups, sprint planning, and retrospectives.

The cost of choosing a quick, easy solution now instead of a better approach that would take longer. Accumulates over time and slows development.