What are the potential pitfalls of using include() versus require() in PHP programming?

Using include() in PHP can lead to potential pitfalls such as including a file multiple times, which can cause redeclaration errors if the file contains function or class definitions. On the other hand, using require() ensures that the file is included only once, preventing such errors. To avoid these issues, it is recommended to use require() when including files that contain essential code that should not be included multiple times.

// Using require() instead of include() to avoid redeclaration errors
require('essential_file.php');