What are the different types of PHP keywords and definitions?

The different types of PHP keywords are:

1. abstract – Declare a class as abstract.
2. and – A logical operator.
3. as – Used in the for-each loop.
4. break – Break out of loops and switch statements.
5. callable – A data type that can be executed as a function.
6. case – Used in the switch conditional.
7. catch – Used in the try..catch statement.
8. class – Declare a class.
9. clone – Create a copy of an object.
10. const – Define a class constant.
11. continue – Jump to the next iteration of a loop.
12. declare – Set directives for a block of code.
13. default – Used in the switch statement.