Here is a comparison between Interface, Abstract class, and Trait in PHP. Let’s take a look at that side-by-side comparison in a table-
| Criteria / Rule | Interface | Abstract Class | Trait |
|---|---|---|---|
| Can be instantiated |  No | No | No |
| Can contain public property | No |  Yes | Yes |
| Can contain protected property | No | Yes | Yes |
| Can contain private property | No | Yes | Yes |
| Can contain public constant | Yes | Yes | Yes |
| Can contain protected constant | No | Yes | Yes |
| Can contain private constant | No | Yes | Yes |
| Can contain public abstract method(signature only) | Yes | Yes | Yes |
| Can contain protected abstract method(signature only) | No | Yes | Yes |
| Can contain private abstract method(signature only) | No | No | Yes |
| Can contain public method(normal) | No | Yes | Yes |
| Can contain protected method(normal) | No | Yes | Yes |
| Can contain private method(normal) | No | Yes | Yes |
| Can inherit from normal class | No | Yes | No |
| Can inherit from abstract class | No | Yes | No |
| Can implement interface(s) | Yes | Yes | No |
| Can use trait(s) | No | Yes | Yes |
| Can be inherited/used multiple times from a single class/interface/trait | Yes | No | Yes |
Now let’s discuss in detail, about the use cases and when should we choose one of these, in our PHP code.
