Phase - definition of phase

Definition of  phase:A phase is define as any homogeneous and physically distinct part of a system which is separated from other part of a system by bounding surface.The term homogeneous means that system has identical physical properties and chemical composition throughout the whole of the system.
Number of phase: 
(1)for gas:there are one phase as they are completely misible in all proportion.
(2)for liquid: there are no of phase equal to the no of layer.for completely misible liquid the no of phase is one.
(3)for solid:In general every solid constitute is a single phase except when a solid solution is form.for solid solution the no of phase is 1.
No of component: The minimum no of independent chemical consititute by means of which each and every phase of the system can be expressed .Independent chemical constitute means whose conc can be varied independently of other constite of the system.
Degree of freedom: The degree of freedom of the system  can be expressed as the no of factor such as tempreture,pressure and concentration which can be varied  independently without altering the no of phase of the system.
Phase Rule:The various condition of equilibrium between phase such as no phase, no of  component,Degree of freedom can be correlated with one another with the help of a general rule ,known as a phase rule.Gibbs phase rule is 
[ F=C-P+2 ]