In simple words evolution is a change in any kind of living thing over generations. evolution may be divided into sector. for example mutation, the sex and recombination of the DNA and the gene flow.

This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
     Evolution is the gradual and slow process of change that occurs in living species.  The living organisms adapt themselves to the environment and slowly change their biological systems and processes in order to live more efficiently in that environment.  
    Organisms also have the capability to reproduces species that are more capable than the previous generations.  Due to improvements in the genes and traits, the successive generations of species evolve in each organ of the body.  The shape, size, constitution, and purpose of organs change to the better.  Some unused organs will slowly disappear from the species.

    The evolution depends on the flexibility of the organism in learning the new environment and changing its metabolism and other processes throughout its body.  Evolution happens through mutation in the DNA, RNA genomes.