Multiple automatic wheres

I was seeing in CodeIgniter that there is a way to insert multiple 'where' into class DB :

Example:

$this->db->where('id', 1)
     ->where('name', 'Jão')
     ->where('lastname', 'Fulaninho')
     ->get('users')
     ->result();

The question here is that in where some words are automatically inserted into each new where that I put up where (...) or where (...) and so on.

What is the name of this form of programming in POO . So I make my own classes that way.