what is the full form of …

The full form of RTI is Right to information.
"The Right to Information Act 2005 (Act No. 22/2005)[1] is a law enacted by the Parliament of India giving citizens of India access to records of the Central Government and State Governments. The Act applies to all States and Union Territories of India, except the State of Jammu and Kashmir - which is covered under a State-level law. Under the provisions of the Act, any citizen (including the citizens within J&K) may request information from a "public authority" (a body of Government or "instrumentality of State") which is required to reply expeditiously or within thirty days. The Act also requires every public authority to computerise their records for wide dissemination and to proactively publish certain categories of information so that the citizens need minimum recourse to request for information formally.