Children between 18 months and 3 years of age are referred to as toddlers.  They learn that they are a separate being from their parents, and as such they want to do everything by themselves!  They walk, climb, run, and get into everything, as thy should.  That helps them develop gross fine motor skills.  

Parental job at that stage is to make sure that the toddler explores the world in a safe way.  Also, parents should encourage exploration and learning.  If they are over-protective or criticize the child for "accidents", the child may develop doubt in own abilities and not want to take on new challenges.

Best regards.