Wish I could understand all this 😦
here are some links:
LOL, I found something for me on this stackoverflow discussion threadm, just for dumb people like me , http://stackoverflow.com/questions/1852093/abstract-keyword-in-php
The definition is mentioned in many places on the net, now I will try to give you an example:
“abstract” ensures that you follow a specific logic, e.g. a ticket’s material is ALWAYS “paper”, or a creditcare must always have a “code”. This is important if you work in a big company which has strict standardisation or if you want to ‘force’ your developers to follow a specific structure, so their code won’t end up in a mess.