Solids have three characteristics: fixity, stability and possession.

Fixity: solids have a certain volume and shape and are not easy to be compressed or stretched. Their shapes and sizes can remain unchanged under certain conditions.

Stability: Solid has high stability and is not easy to be damaged or deformed. The interaction between solid molecules is very strong, which enables them to maintain a stable structure.

Possession: Solid has a certain space of occupation and has the characteristics of resisting movement. Because of the strong interaction between solid molecules, they can maintain a certain shape and position.

In physics, these characteristics of solids are determined by the interaction between solid molecules and the internal microstructure of solids. The interaction between solid molecules enables them to maintain a stable structure, and the microstructure inside the solid determines its physical properties.

In daily life, there are many examples of solids, such as metals, plastics and ceramics. These materials have a fixed shape and volume, are not easy to be compressed or stretched, and have high stability and anti-movement.

These three characteristics of solids are widely used in our daily life and scientific research.

Fixity: In architecture, manufacturing and design, we all need to use solid materials with fixed shape and volume. For example, materials such as steel, cement and glass can be used to build bridges, buildings and various mechanical equipment because of their fixity.

Stability: The high stability of solids makes it an ideal choice for storing and transporting various substances. For example, metals such as gold, silver and copper are often used as currency, jewelry and various industrial products because of their stable chemical properties.

Possession: In chemical reactions, solids are usually used as catalysts or reactants. For example, in the production of cement, limestone and clay react chemically at high temperature to produce solid cement. In this process, solids occupy a certain space and have the characteristics of resisting movement.

In a word, the three characteristics of solids are fixity, stability and possession. These characteristics make solids have important application value in production and life, and also provide an important foundation for us to know and understand the material world.