The 1951 Convention Relating to the Status of Refugees is the key legal document that defines who is a refugee, their rights, and the legal obligations of State parties
Asylum-Seekers: people who are seeking international protection. An asylum-seeker is someone whose claim has not yet been finally decided by UNHCR or authorities of the country in which he or she has requested refugee status. Not every asylum-seeker will ultimately be recognized as a refugee, but every refugee is initially an asylum-seeker.
Stateless Persons: people who are not recognized by any country as citizens and who, consequently lack the protections flowing from citizenship. Article 1 of the 1954 Convention relating to the Status of Stateless Persons sets out the criteria for statelessness in international law.
Internally Displaced People (IDPs): people who are forcibly displaced within their countries of origin or habitual residnece but who have not cross an internationally recognized State border. People may be internally displaced as a result of armed conflicts, situations of generalized violence, violations of human rights or natural or human-made disasters.
Returnees: refugees who choose voluntarily to return to their country of origin, or in some circumstances, be assisted to return by UNHCR and receive support after they arrive