What does the red color on the national flag of China stand for?

The Resolution of China People's Political Consultative Conference on the Capital, Calendar, National Anthem and National Flag of People's Republic of China (PRC) and the Measures for Flag Making adopted by the CPPCC Presidium stipulate that:

The national flag of China people * * is a five-star red flag, rectangular and red, symbolizing the revolution, and the ratio of length to width is three to two. There are five yellow five-pointed stars on the upper left of the flag, symbolizing the great revolutionary unity under the leadership of the * * * production party. The stars use yellow to symbolize the light on the red earth.

A star is larger, and its circumscribed circle diameter is 3/ 10 of the flag height, on the left side; The four stars are relatively small, and the diameter of the circumscribed circle is110. They arch on the right side of the big star, each with an angle pointing directly at the center of the big star, expressing the wishes of hundreds of millions of people to the Greater China * * * production party, as if all the stars arch north. The flagpole cover is white to distinguish it from the red flag.

Extended data

1In July, 949, Comrade Zeng, an ordinary economic worker in Shanghai, saw a notice in the newspaper soliciting the design of China people's national flag, and took an active part in the design work. It took him less than a month to complete the design of the five-star red flag pattern and sent it to Beijing in mid-August.

1On September 25th, 949, comrades fully affirmed the five-star red flag pattern that had been designed, pointing out that this pattern showed the great unity of the revolutionary people in our country. Great unity is needed now and in the future.

1949 On September 27th, the first plenary session of China People's Political Consultative Conference formally passed a resolution, and the people and national flag of China were the five-star red flag. On June 1 949+1October1day, Comrade Mao Zedong personally raised the first five-star red flag in Tiananmen Square.

References:

Baidu Encyclopedia-China People and the National Flag