JavaScript is a versatile programming language primarily used for creating interactive elements on web pages. It was initially developed by Brendan Eich at Netscape Communications Corporation in 1995 and has since become one of the most popular programming languages in the world.

JavaScript is commonly used to add dynamic behavior to web pages, such as:

1. Interactivity: Enabling user interactions like form validation, button clicks, and animations.
2. Manipulating HTML/CSS: Dynamically changing the content and styles of a webpage.
3. Handling Events: Responding to user actions like clicks, scrolls, and keyboard inputs.
4. AJAX: Asynchronous JavaScript and XML, used to send and receive data from a server without reloading the entire page.
5. Client-side Validation: Checking user input before submitting forms to the server.

Syntax:

JavaScript syntax is similar to other C-style languages like Java and C++. Here's a basic example:

// Defining a function
function greet(name) {
    console.log("Hello, " + name + "!");
}

// Calling a function
greet("John");