#definitions of limits

Limits: 

          A useful definition is provided by McGraw Hill: "Two extreme permissible sizes of a part between which the actual size is contained, are called Limits".

Fits:

          The relationship between two parts, which are to be assembled, with respect to difference of their sizes, before assembly is called 'Fit'.

          It is the general term used to signify the range of tightness or looseness that may result from the application of a specific combination of allowances and tolerances in  mating parts.

Tolerance:

          The total permissible variation of a size is called Tolerance. It is the difference between maximum and minimum limit of size.