If you’ve been paying attention so far, you might have picked up a theme in programming—shortcuts. Defining our own functions gives us an easier way to repeat similar code throughout a program. But some tasks are so common that the language comes with them by default.

PHP comes with a number of built-in functions. These functions—also known as internal functions— can be invoked without writing them ourselves. In this lesson, we’ll explore some useful built-in functions and empower you to discover new built-in functions yourself. This will quickly become an essential part of your developer toolkit!

Let’s get started.


We’ve been using echo to print information to the console. echo is NOT a function (it’s a “language construct”). But, one little PHP quirk is that we can use it in a way that looks a lot like invoking a function—we can wrap an argument for echo in parentheses.

echo can also be used to print multiple string arguments, but unlike a function, for this feature to work we must NOT wrap them in parentheses. Take a look at the code editor; we’ve provided some examples of using echo with and without parentheses. If you’d like, uncomment the broken code to see the error it causes.

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