Question

What is the microarray experiment?

Answer 1

in terms of viruses, microarray is basically comparing a whole library of known viral genome sequences to an unknown sample in the hopes of identifying that virus.

Answer 2

in most cases microarray implicitly means RNA expression microarray. the idea is quite simple: u glue short RNA sequences on a glass slip, they are commonly known as oligonucleotides. . the array thingy is just to cram lots of this glued points together. now comes the cool part, RNA extracted from the cell type/tissue of interest is hybridized
a-t c-g (i hope i didnt mix this part) and stays put. this RNA isnt just RNA, it is marked with a fluorescent color (dye). the more RNA more color readout will be captured (using a camera of course). depends on the make of the array. the readout is either absolute or comparative (to a control sample).
attached is just an image i found. the control is green, the sample is red. if u have more sample rna - red readout. more sample green. in between - yellows (red+green is yellow. try in photoshop)

Answer 3

http://www.nature.com/scitable/content/microarray-6656746

Microarray is a technique used to study the expression of several thousand genes at once. Check out the video posted above