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defclass

:initform - Default slot value. Evaluated at make-instance time.
:initarg - Defines a keyword to make-instance that sets slot value
:reader - slot option to define a method to read a slot value
:writer - makes method to set slot value
:accessor - makes two methods, a reader and a setf writer
:allocation - determines if slot is shared (:class) or normal (omit or :instance)
:default-initargs - Allows default values (ala initform) of already existing initargs without having to respecify slot.
:type - Allows (but does not require) compiler to make type assumptions
:documentation - associates a doc string with a slot
See "Define-Class" macro for simplified interface with automatic initform, initargs and accessor.

No default keywords. Only if specified via :initarg.
slot-value - Atomic function to read the value of a slot. You almost always want to use accessors instead.
(setf slot-value) - Atomic function to write the value of a slot. Normally use a writer or (setf Accessor) function, but this internal version would be called when writing your own custom writer.
initialize-instance - called by make-
instance, and the best place to put after methods to do bookkeeping on instance.

Similar to defun but can replace a var in the arglist with a (Var Type) pair
If no generic function exists when method defined, one is created
Most built-in data types and all classes can be specialized upon
Cannot specialize on &optional or &key args
For primary methods, only the single most specific method is called
:before methods, all are executed in least-specific to most-specific order
:after methods, all are executed in most-specific to least-specific order
:around methods are the only type that can prevent primary methods from firing
setf forms are considered primary methods, and thus can have before, after, and around methods associated with them
Cannot add a method to a built-in standard (i.e. non-generic) function