The sequence in which various living things are interrelated through a series of relationships between eating and being eaten is called food chain in ecology.

According to the relationship between organisms, the food chain can be divided into predatory food chain, scavenging food chain (scavenging food chain) and parasitic food chain. All kinds of living things obtain the energy needed for survival, growth and reproduction in their unique ways. Producers' fixed energy and substances are transferred between organisms through a series of feeding relationships, such as herbivores feeding on plants and carnivores preying on herbivores. This one-way chain connection between different organisms through food is called food chain. A complete food chain is built by producers and consumers, and the source begins with the photosynthesis of producers locking in solar energy.

In fact, in nature, every animal does not eat only one kind of food. Therefore, multiple food chains will be intertwined to form a complex food web.