What is tribo electric charging

The process of electron transfer as  a result of two objects coming into frictional  contact and then separating is known as triboelectric charging.

Explanation :

The prefix tribo means ' to rub '.Triboelectric effect  is a type of contact electrification in which certain materials become electrically charged  after they come into frictional contact with a different material ( viz. rubbing glass  with fur , aplastic comb with hair. )  Thus ,   as a result of rubbing one object with another , one of the object gains electrons over its surface , and therefore becomes  negatively charged  , and simultaneously the other object loses electron from its surface ,therefore becomes positively charged . Different materials have different tendencies to  gain or lose electrons  from  their surfaces ,hence  which material becomes positive or negative depend on the relative tendencies of materials involved  to gain or lose electrons.