The onclick event in JavaScript is a type of event that is triggered when a user clicks on an HTML element, such as a button or a link. It allows the developer to specify a JavaScript function that is executed when the element is clicked.

The basic syntax for using the onclick event in JavaScript is as follows:

element.onclick = function() {
// code to be executed when the element is clicked
};

Alternatively, you can also use the event listener syntax to attach an onclick event, like this:

element.addEventListener('click', function() {
// code to be executed when the element is clicked
});

In both cases, you would substitute "element" with a reference to the actual HTML element you want to attach the event to, and the code inside the function would be executed when the element is clicked by the user.