Parti Keadilan Rakyat (PKR) was formed in April 1999, seven months after the sacking of then deputy prime minister Anwar Ibrahim triggered Reformasi street protests that shook Malaysian politics.
The party was originally named Parti Keadilan Nasional (National Justice Party), but changed this to PKR, which means People's Justice Party, following a 2003 merger with Parti Rakyat Malaysia.
The Malay-led multiracial party sits on the centre-left of Malaysian politics, in a country where most political parties are set up along racial lines. PKR has some 500,000 members.
PKR's "ketua umum", or leader, an unelected post, is Anwar. He is serving a five-year jail sentence, from 2015, for a sodomy offence.
His wife Wan Azizah Wan Ismail is PKR's president, and eldest daughter Nurul Izzah Anwar is one of the six vice-presidents.
PKR's deputy president is Datuk Seri Azmin Ali, who is also Menteri Besar of Selangor.
The other vice-presidents are Mr Tian Chua, Mr Shamsul Iskandar Md Akin, Mr Rafizi Ramli, Dr Xavier Jayakumar Arulanandam and Dr Shaharuddin Badaruddin.
The party leads the Pakatan Harapan government in Selangor, Malaysia's most industrialised state.
PKR today has 28 lawmakers in the federal Parliament, and 51 in the various state legislatures.