DNA sequencing is the process of determining the order of nucleotides in a DNA fragment. The first DNA sequencing method, called Sanger sequencing, was developed in 1975 and involves copying DNA fragments and labeling the fragments to determine the sequence. DNA sequencing is useful for scientists as it allows study of what DNA codes for through comparative and functional genomics. While it improves healthcare and agriculture, a disadvantage is the risk of providing an incorrect DNA sequence.