What is Ontology Learning ?

An Ontology is a formal representation of a set of concepts and the relationship between these. For Example, we have lot of users bookmarking a post. Let us take a particular post. Some people bookmark it as ‘human’ and some others as ‘mammal’. By ontology learning, it means  (after analyzing posts similar to those) classifying ‘Human’ as a type of ‘Mammal’ so that we have structured data.