About PHP errors 
When coding in PHP, a series of errors can be made which can be classified basically as:
Parse Error
It can be considered as syntax errors, such as:
a) Unclosed quotes,
b) Missing or Extra parentheses,
c) Unclosed braces or
d) Missing semicolon.
Such Parse errors can be considered the most common.
Does not interrupt...
... the flow of the running script
Warning Error
The main occurrence of a Warning can happen when adding a non-existent file or using an incorrect number of parameters in a given function.
Does not interrupt...
... the flow of the running script
Notice Error
An error called Notice error, has practically the same purpose as the Warning error.
A characteristic Notice error occurs when trying to access an undefined variable.
Does not interrupt...
... the flow of the running script
Fatal Error
A Fatal error happens when what was written as code is not understood.
Interrupts the flow of the running script