Darwin`s theory of evolution is a comprehensive explanation for how species change over time. It is based on several key concepts, including natural selection, struggle for existence, and survival of the fittest.

1. Natural selection: This is a process by which certain traits become more or less common in a population over time based on their ability to survive and reproduce in a given environment. It is a central mechanism in Darwin`s theory.

2. Struggle for existence: This concept describes the competition organisms face for limited resources, such as food, mates, and territory. Individuals with advantageous traits have a higher chance of surviving and reproducing, while those with less beneficial traits are more likely to struggle.

3. Survival of the fittest: This refers to the idea that individuals with traits that are well-suited for their environment have a higher chance of survival and passing on their genes to the next generation.

4. Inheritance of acquired characters: This is not a part of Darwin`s theory of evolution. It was proposed by an earlier scientist, Jean-Baptiste Lamarck. Lamarck suggested that acquired characteristics during an individual`s lifetime could be passed on to the next generation. However, this idea has been largely disproven by modern genetics.

Overall, Darwin`s theory of evolution provides