The four fundamental characteristics of Pu'er Tea include its geographical origin, varietal traits, physical appearance, and taste profile.

1. **Geographical Origin**: Pu'er tea is primarily produced in areas such as Xishuangbanna, Pu'er City, and Lincang City in Yunnan Province. These regions are characterized by a humid climate, misty conditions, deep soil layers, fertile land, and an absence of pollution, providing a superior ecological environment for the growth of high-quality tea plants.

2. **Varietal Traits**: The raw material used for making Pu'er tea is the large-leaf variety native to Yunnan, also known as the arbor-type large-leaf variety. Its buds and leaves are robust, covered with white down, and rich in chemical components, resulting in a fragrant and flavorful tea.

3. **Physical Appearance**: One of the most distinctive features of Pu'er tea compared to other teas on the market is its shape. Pu'er tea is mainly stored in compressed forms such as bricks, cakes, tuos, melons, spheres, and other less common shapes.

4. **Taste Profile**: The taste profile of Pu'er tea includes differences between raw (sheng) and ripe (shou) varieties. Raw tea does not undergo artificial fermentation, relying instead on natural fermentation, and is typically best after 5 to 10 years, featuring a dark green color, strong sensations of salivation and a refreshing aftertaste. Ripe tea is processed through special fermentation methods, presenting a dark black color in the cake, a reddish-brown infusion, and a thick and smooth mouthfeel.

These characteristics together form the unique appeal of Pu'er tea, making it stand out among all teas.