These postcards are marked Start of Spring, the first solar term of the year, which began this year on Feb 4 and ends on Feb 18. [Photo/ntfabu.com]

Luo Bangshun, vice-chairman of the Nantong primary and Secondary Schools' Philatelic Association, is a retired teacher who has collected stamps and other philatelic items for more than 50 years and has given lectures on stamps to over 5,000 students.

This postcard has a fan-shaped stamp featuring the words Rain Water, one of the 24 solar terms, which signals an increase in rainfall and rise in temperature. On the left, it features a picture and words related to the solar term. [Photo/ntfabu.com]

Luo has also prepared a collection of 24 solar term-themed stamps to teach students about the 24 solar terms.

The traditional Chinese lunar calendar divides the year into 24 solar terms, a concept that was included on UNESCO's Representative List of the Intangible Cultural Heritage of Humanity in 2016.

This postcard has a fan-shaped stamp printed with the words Awakening of Insects, one of the 24 solar terms, which also signals an increase in rainfall and rise in temperature. On the left, it has a picture and words related to the solar term. [Photo/ntfabu.com]

The 24 solar terms are determined by changes in the sun's position in the zodiac during the year. They were first used in China and now are followed in many other parts of the world. In China, the 24 solar terms were created thousands of years ago to guide agricultural production. They also reflect China's rich history through the seasonal festivals, special foods, cultural ceremonies, family gatherings and even healthy living tips that correspond with each solar term.

This postcard has features related to Awakening of Insects, including pears. In China, there is a custom of eating pears during the Awakening of Insects. [Photo/ntfabu.com]