  The unitary isobar model MAID2007 has been developed to analyze the world
data of pion photo- and electroproduction. The model contains both a common
background and several resonance terms. The background is unitarized according
to the K-matrix prescription, and the 13 four-star resonances with masses below
2 GeV are described by appropriately unitarized Breit-Wigner forms. The data
have been analyzed by both single-energy and global fits, and the transverse
and longitudinal helicity amplitudes have been extracted for the four-star
resonances below 2 GeV. Because of its inherent simplicity, MAID2007 is well
adopted for predictions and analysis of the observables in pion photo- and
electroproduction.
