Mitosis is the process of replication that occurs in all cells, it is how we live and grow. In fact, during your lifetime, your cells will undergo the process of Mitosis about Ten thousand billion times!
Mitosis begins with an interphase, where DNA replicates. There then follows four phases, the first is prophase, the DNA tangle named chromatin condenses and coils around proteins. Following this is the Metaphase. This is the longest phase where the chromosomes line up and attach to microtubules in the cell; they are pulled apart in the anaphase.
Finally, during the telophase, two new cells, both with full sets of 46 chromosomes exist, perfect clones.
From Crash Course: Biology on YouTube by Hank Green.