A DNA microarray (also commonly known as DNA chip or biochip) is a collection of microscopic
DNA spots attached to a solid surface. Scientists use DNA microarrays to measure the expression levels
of large numbers of genes simultaneously or to genotype multiple regions of a genome.

Each DNA spot contains picomoles (10−12 moles) of a specific DNA sequence, known as probes (or
reporters or oligos). These can be a short section of a gene or other DNA element that are used to hybridize
a cDNA or cRNA (also called anti-sense RNA) sample (called target) under high-stringency conditions.
Probe-target hybridization is usually detected and quantified by detection of fluorophore-, silver-, or
chemiluminescence-labeled targets to determine relative abundance of nucleic acid sequences in the target.

Each DNA spot contains picomoles (10−12 moles) of a specific DNA sequence, known as probes (or
reporters or oligos). These can be a short section of a gene or other DNA element that are used to hybridize
a cDNA or cRNA (also called anti-sense RNA) sample (called target) under high-stringency conditions.
Probe-target hybridization is usually detected and quantified by detection of fluorophore-, silver-, or
chemiluminescence-labeled targets to determine relative abundance of nucleic acid sequences in the target.