What is camelCase? A Complete Guide to Naming Conventions

In the world of computer programming, consistency is key. The way we name things, from variables and functions to classes and files, has a significant impact on the readability and maintainability of our code. This is where naming conventions come in. They provide a shared set of rules that help development teams write code that is clear, predictable, and easy to understand.

One of the most common and recognisable naming conventions is camelCase. If you have ever written a line of JavaScript, it is highly likely you have encountered it. But it is just one of several styles, each with its own specific uses and community preferences. Understanding these conventions is a fundamental skill for any developer.

This guide will provide a thorough explanation of camelCase and other popular naming styles like PascalCase, snake_case, and kebab-case. We will explore their origins, look at practical examples, and discuss when to use each one in different programming languages. We will also point you to some handy tools, like our very own Case Converter, to help you switch between them effortlessly.

What is camelCase?

camelCase is a naming convention where the first word of a compound phrase is written in lowercase, and the first letter of each subsequent word is capitalised, with no spaces or punctuation in between. The name itself comes from the "hump" created by the capital letters in the middle of the phrase, much like a camel.

For example, if we have a variable that stores a user's first name, using camelCase it would be written as firstName.

Examples of camelCase:

• myVariable
• calculateTotalAmount
• userName
• backgroundColor

camelCase is particularly popular in the JavaScript world and is the standard convention for naming variables and functions. It is also widely used in other languages like Java and Swift.

The Main Variants: Upper and Lower CamelCase

While "camelCase" usually refers to the style starting with a lowercase letter, it is technically lowerCamelCase. There is also a variation called UpperCamelCase, more commonly known as PascalCase.

PascalCase (UpperCamelCase)

PascalCase is identical to camelCase, except the very first letter is also capitalised. This style is often used for naming constructs that represent a "type" or a "class". Think of them as titles or proper nouns in the code.

For instance, a class that defines a user object would be named User or UserProfile.

Examples of PascalCase:

• MyComponent (Common in React components)
• HttpRequest
• CustomerModel
• ApplicationSettings

The distinction is important. In many languages, the casing of the first letter signals the nature of the identifier. A lowercase start suggests an instance or a function (like a verb), while an uppercase start suggests a blueprint or a class (like a noun).

Other Popular Naming Conventions

Beyond the world of humps, several other case styles are prevalent in programming. Let's explore the most common ones.

snake_case

As the name suggests, snake_case separates words with an underscore (_). All letters are typically lowercase. It creates a long, flat, and winding identifier, much like a snake.

This convention is the standard in Python for naming variables and functions (as per the PEP 8 style guide). It is also very common in database programming for naming tables and columns (e.g., user_profiles, first_name).

Examples of snake_case:

• my_variable
• calculate_total_amount
• user_name
• background_color

There is also a version called SCREAMING_SNAKE_CASE (or CONSTANT_CASE), which is all uppercase. This is the universal standard for declaring constants in most programming languages. Constants are variables whose values should not change during the program's execution.

Examples of CONSTANT_CASE:

• MAX_CONNECTIONS
• API_KEY
• DEFAULT_TIMEOUT

kebab-case

kebab-case is similar to snake_case, but it uses a hyphen (-) to separate words instead of an underscore. You can imagine the words being skewered by the hyphen, like a kebab.

This style is not often used within programming languages themselves because the hyphen is typically interpreted as a subtraction operator. However, it has found a strong foothold in other areas of web development.

Examples of kebab-case:

• my-variable
• background-color
• font-size

kebab-case is the standard for naming CSS properties and is also the most common convention for URL slugs (like the one for this article: what-is-camelcase) and HTML element attributes.

When to Use Each Naming Convention: A Language Guide

The choice of naming convention is rarely a matter of personal preference. It is usually dictated by the programming language, framework, or team-specific style guide. Following the established convention for a particular technology makes your code more idiomatic and easier for other developers to understand.

Here is a general guide:

Following these conventions is a mark of a professional developer. It shows that you care about writing clean, readable, and maintainable code. When in doubt, always refer to the official style guide for the language or framework you are using.

Effortless Conversion

Switching between these different case styles manually can be tedious and prone to error. That is why we built the Case Converter tool. It allows you to instantly convert any text between camelCase, PascalCase, snake_case, kebab-case, and more. It is a simple but powerful utility that can save you a lot of time and effort, especially when working across different languages and platforms.

Whether you are a seasoned developer or just starting, mastering naming conventions is a simple step that can dramatically improve the quality of your work. They are the silent grammar of your code, and using them correctly helps everyone speak the same language.