Umno's general assembly is the most closely watched political event in Malaysia annually, except when there is a general election.
In the past, the issues raised at the five-day congress, attended by party members from all over the country, have resulted in new or tweaked government policies. Key speeches are broadcast live on radio and TV, with Umno the only political body to be given this privilege.
Love or loathe it, the reason for Umno's power is its outsized position in Malaysian politics.
The Malay nationalist party is the linchpin of the 13-party Barisan Nasional (BN) coalition that has governed Asean's third biggest economy - after Indonesia and Thailand - since independence. Umno has 88 seats in the federal Parliament, 40 per cent of the 222 seats in total. The party with the next biggest number of seats is the opposition Democratic Action Party with 38.
Nineteen, or half, of Malaysia's 38 full Cabinet ministers are from Umno. They include Prime Minister Najib Razak and Deputy Prime Minister Ahmad Zahid Hamidi, who are appointed by the party.
Umno holds its internal elections every three years, but these have been postponed several times when the party faced turmoil. The next party elections will be held after the general election, which must be held by 2018.
The party has 3.5 million members and 191 divisions in 12 of 13 Malaysian states, under which there are nearly 22,000 Umno branches.
Umno is not present only in Sarawak, because of its special arrangements with its BN coalition partners there when Sarawak became part of Malaysia in 1963. Sarawak has 31 federal seats, mostly filled by BN parties.
The 191 divisions of Umno mirror the other 191 parliamentary seats of the 222-seat Parliament.