What is the Usage of apex program with VisualForce page in Salesforce

Question

What is the Usage of apex program with within VisualForce page?

Answer 1

When you want to call apex class in VisualForce page we have to declare in the following format.

1

< Apex : page controller = “class name “ >

Whenever we call a VisualForce page in which controller attribute is defined it will first create an object for the apex class which is defined in the controller. When an object is created for the apex class first it involves the constructor.