INTEGRAL is an optical fiber system to perform simultaneous two-dimensional spectroscopy (i.e. Integral Field Spectroscopy). It is the last of a serie of optical fiber instruments developed at the Instituto de Astrofisica de Canarias. Since 1998 it is available at the 4.2m WHT as a common user instrument, and it has been used in a number of galactic and extragalactic programs. This presentation is intended to have two main parts. In a first part, we will discuss the main technical advantages and disadvantages of the optical fiber systems with respect to other IFS approaches. This includes relevant issues for galaxy observations such as dynamic range and sky subsraction. In a second part we will present the main scientific extragalactic programs carried out with INTEGRAL. This will include results on the core of nearby galaxies, Seyfert galaxies, ultraluminous infrared galaxies, and gravitational lenses. Through all the presentation especial emphasis will be done in illustrating with real data the capabilities of this type of instruments.