Genetic Engineering:
The technique of removing, modifying, or adding genes to a DNA molecule in order to change the information it contains. By changing this information, genetic engineering changes the type or amount of proteins an organism is capable of producing, thus enabling it to make new substances or perform new functions.
From: usinfo.state.gov/journals/ites/0903/ijee/glossary.htm

A broad term to describe applications of computer technology and information science to organize, interpret, and predict biological structure and function. Bioinformatics is ususally applied in the context of analyzing DNA sequence data.
From : www.plpa.agri.umn.edu/scag1500/definitions.html
Microarray
A technology using a high-density array of nucleic acids, protein, or tissue for examining complex biological interactions simultaneously which are identified by specific location on a slide array. A scanning microscope detects the bound, labeled sample and measures the visualized probe to ascertain the activity of the genes of interest in genotyping, cellular studies, and expression analysis.
From : www.qdots.com/live/render/content.asp