How micro service is different from regular web service

Question

i often developed web service using asmx, wcf and web api. when i heard the term micro service then just do not understand what it is and how micro service is different from the web service what we developed with asmx, wcf and web api.

 

so please some one who knows what is micro service then please share the knowledge that what it is and how it is different from the web service what we developed with asmx, wcf and web api with a example. thanks