[[Microarray]]s usually consist of a grid of short nucleotide [[oligonucleotide|oligomers]], known as "[[Molecular probe|probes]]", which are typically arrayed in a gridarranged on a glass slide.<ref name=pmid24479125>{{cite journal | vauthors = Romanov V, Davidoff SN, Miles AR, Grainger DW, Gale BK, Brooks BD | title = A critical comparison of protein microarray fabrication technologies | journal = The Analyst | volume = 139 | issue = 6 | pages = 1303–26 | date = March 2014 | pmid = 24479125 | doi = 10.1039/c3an01577g | bibcode = 2014Ana...139.1303R }}</ref> Transcript abundance is determined by hybridisation of [[Fluorescence|fluorescently]] labelled transcripts to these probes.<ref name="#17095434">{{cite journal | vauthors = Barbulovic-Nad I, Lucente M, Sun Y, Zhang M, Wheeler AR, Bussmann M | title = Bio-microarray fabrication techniques—a review | journal = Critical Reviews in Biotechnology | volume = 26 | issue = 4 | pages = 237–59 | date = 2006-10-01 | pmid = 17095434 | doi = 10.1080/07388550600978358 | citeseerx = 10.1.1.661.6833 | s2cid = 13712888 }}</ref> The [[Fluorometer|fluorescence intensity]] at each probe ___location on the array indicates the transcript abundance for that probe sequence.<ref name="#17095434" /> Groups of probes designed to measure the same transcript (i.e., hybridizing a specific transcript in different positions) are usually referred to as "probesets".
Microarrays require some genomic knowledge from the organism of interest, for example, in the form of an [[DNA annotation|annotated]] [[genome]] sequence, or a [[Library (biology)|library]] of ESTs that can be used to generate the probes for the array.<ref name="pmid12117754" />
