What is the purpose of the trait in PHP?

Trait is a code reuse mechanism that allows methods from classes to be introduced and combined in PHP. It is similar to partial implementation of a class, and can be used by multiple classes at the same time.

The functions of Trait include:

1. Code reuse: traits can define a set of methods that can be used in multiple classes, preventing the need to repeat code.
2. To solve the issue of multiple inheritance: PHP does not support multiple inheritance, but by using Traits, you can incorporate multiple Traits into a class to combine methods from different classes.
3. Glue layer of providing methods: Traits can serve as a collection of methods for classes, providing a way to combine methods from different classes.
4. Resolve diamond inheritance issue: Traits can prevent the diamond inheritance problem caused by multiple inheritance, as Traits are unrelated between classes and do not cause conflicts.

In conclusion, Trait offers developers a more flexible way of organizing and reusing code, which can improve the readability and maintainability of the code.