what is a genetic drift

a small random change in the DNA
the process in which humans select for or against particular features
the movement of genes in/out of a population
any changes in the allelic frequencies in a population that is due to chance

Genetic drift is any changes in the allelic frequencies in a population that is due to chance. It is a random process that can lead to certain alleles becoming more or less common in a population over time, without any selective pressure or advantage.