China is holding the widely-anticipated fourth plenary session of the 19th Central Committee of the Communist Party of China (CPC) in Beijing starting from Monday, with a focus on improvements to the country's socialist system and governance capacity.

But wait, what exactly is the "fourth plenary session of 19th CPC Central Committee?"

The highest decision-making bodies of the CPC, China's ruling party, are composed of two parts: the CPC National Congress, and the CPC Central Committee elected by it.

The National Congress is held once every five years and is usually attended by over 2,300 delegates. The latest one, the 19th CPC National Congress in October 2017, elected the current 19th CPC Central Committee (with 204 full members and 172 alternate members) for a five-year term.

"When the National Congress is not in session, the Central Committee shall carry out its resolutions, direct all Party work, and represent the CPC in external relations," according to the CPC constitution.

Seven plenary sessions are usually held during the five-year tenure of the Central Committee member.

The Party constitution required such gatherings to be convened at least once annually. Each plenum has its own agenda.

The first plenary sessions of a CPC Central Committee are always held right after the CPC National Congress, which elect the Party's leadership.

For example, at the first plenary session of the 18th CPC Central Committee in November 2012, then-Chinese Vice President Xi Jinping was elected its general secretary for the first time. 

Third plenary sessions are known for making major decisions on the country's course for future development: the third plenary session of the 11th CPC Central Committee in 1978 unveiled the country's plan for reform and opening-up.

The fourth gathering often focuses on improvements to CPC's governing capacity and serves as a link between sessions. The ongoing plenum is the fourth plenary session of the 19th Central Committee members.

High on this year's agenda are discussions of upholding and improving the system of socialism with Chinese characteristics and making progress in modernizing China's system and capacity for governance.

A communique is expected to be issued after this four-day meeting.

Here is a review of all such plenary sessions since late 2012: