Short answers, pulled from the story.
The People's Progressive Party formed on the 1st of January 1950 through a merger between two distinct groups. Forbes Burnham led the British Guiana Labour Party while Cheddi Jagan headed the Political Affairs Committee.
General elections took place in 1957 when the party had already split into two factions with Jagan securing nine seats and Burnham winning three seats. Burnham left the party shortly after these results to form the Afro-Guyanese-dominated People's National Congress which established a permanent ethnic divide between the two major parties.
The Kennedy administration suspected Cheddi Jagan was likely a Communist leader and forced a reluctant United Kingdom to aid conservatives and Burnham loyalists in evicting the PPP government. Riots ensued with the hope of removing the Chief Minister from power before Governor Richard Luyt invited rivals to form a government instead.
Janet Jagan ran as the PPP/C candidate for the presidency in the 1997 elections which the party won and she became the first American-born female head of state after this victory. She resigned as president in 1999 due to ill health and was succeeded by Bharrat Jagdeo.
On the 5th of May 2024, the party held its 32nd Congress to address internal ideological questions where delegates voted to remove Marxism-Leninism from their constitution during this gathering. They also deleted socialism from the document while retaining democratic centralism as a core principle.