For writing object oriented programs, common LISP includes a set of operators, collectively they are called CLOS or Common Lisp Object System.
The common objective of LISP is to
• To fit common lisp in a natural way, in terms of functional notation and extending common LISP type
• To provide a smooth growth path and easy transitions for current users of flavors and common loops
• To provide a layered approach
• To provide both platforms for the efficient delivery of applications and language for powerful programing environment