| Property | Actual Class | Abstract Class | Interface |
|---|---|---|---|
| Instances of this can be created | Yes | No | No |
| This can define instance variables and methods | Yes | Yes | No |
| This can define constants | Yes | Yes | Yes |
| The number of these a class can extend | 0 or 1 | 0 or 1 | 0 |
| The number of these a class can implement | 0 | 0 | any number |
| This can extend another class | Yes | Yes | No |
| This can declare abstract methods | No | Yes | Yes |
| Variables of this type can be declared | Yes | Yes | Yes |