The purpose of the process of DNA replication is to pass the genetic information of the organism, specifically of the parent cell, into the new daughter cells; the cells cannot divide if they don't first duplicate the genetic information, or the genes, encoded in their DNA. DNA replication is very important, as it enables cell growth and is essential for the process of reproduction of organisms, as well as the process of evolution.
DNA replication is a biological process in which the DNA molecules are duplicated, or in which the DNA essentially copies itself during cell division. The process is semiconservative, as the two new DNA molecules consist of one parental strand which is copied into one new, complementary daughter strand. Thus, every new DNA double helix is made up of one strand of old DNA (or a strand from the original template molecule) and one strand of new DNA; one of the strands in the parent double helix is conserved into the new molecule.
The four main components that essentially initiate the process of DNA synthesis and DNA replication are substrates, template, primer, and enzymes.
Primers are short sequences of RNA or DNA that start the process of DNA synthesis; RNA primers are used in DNA replication, while DNA primers are used to perform the polymerase chain reaction or PCR. RNA primers are synthesized by the enzyme primase (a type of RNA polymerase).
Primase makes an RNA primer, or short stretch of nucleic acid complementary to the template, that provides a 3' end for DNA polymerase to work on. A typical primer is about five to ten nucleotides long. The primer primes DNA synthesis, i.e., gets it started.
Once the RNA primer is in place, DNA polymerase "extends" it, adding nucleotides one by one to make a new DNA strand that's complementary to the template strand. (Khan Academy)
Some of the most important components in DNA replication are enzymes, especially the DNA polymerase, which is the enzyme that forms new copies of DNA. DNA polymerase adds nucleotides via complementary base pairing (A-T and C-G) to the 3' end of the template strand, one by one, in a 5' to 3' direction, thus synthesizing the new complementary DNA strand. The other enzymes involved in the process of DNA replication are DNA primase, DNA helicase, DNA ligase, and topoisomerase.