Relative Pronoun

See: Pronoun, Relative Clause, Noun Phrase, which.

References

http://en.wikipedia.org/wiki/Relative_pronoun
- A relative pronoun is a pronoun used to mark a relative clause, and having the same referent as the element of the main clause (usually a noun or noun phrase) which the relative clause modifies.
  An example is the English word which in the sentence "This is the house which Jack built." Here which Jack built is a relative clause modifying the noun house. The relative pronoun which marks the relative clause and refers (within the relative clause) to the man being referred to in the main clause. It can be considered to provide a link between the two sentences "This is a house" and "Jack built the house", where the house referred to in each case is the same.
  In providing a link between a subordinate clause and a main clause, a relative pronoun is similar in function to a subordinating conjunction. Unlike a conjunction, however, a relative pronoun does not simply mark the subordinate (relative) clause, but also plays the role of a noun within that clause. For example, in the relative clause which Jack built given above, the pronoun which functions as the object of the verb build. Compare this with "Jack built the house after he married", where the conjunction after marks the subordinate clause after he married, but does not play the role of any noun within that clause.