The increasing needs for long links high bit rate telecommunications systems and for sophisticated guided wave arrangements for fiber sensors led to a rapid evolution of the Integrated Optic technology. Briefly speaking, many progresses have been reported in two main directions. In the first, LiNb03 based waveguides by Ti in diffusion were used to demonstrate various components from low loss high speed modulators or matrix switch arrays to specific chips for fiber sensors like the fiber gyroscope. As a matter of fact, several of these devices begin to be commercially available from different companies. In the second, waveguides are fabricated in semiconductor materials and rapid progresses in the growth techniques led to high quality devices in both GaAs and InP systems leading to realistic previsions for complete monolithic integration. The range of devices already demonstrated is quite impressive as it comprises broadband modulators and switches, multiplexers/demultiplexers, tunable filters, frequency shifters, polarization controllers, switching matrices, multifunction chips for sensors and even some first try of real optoelectronic integration. As a matter of fact, many materials have been used and considered for integrated optics applications. If some kind of active device has to be realized, in general, it is necessary to employ basic materials with the desired properties unless "active" overlayers are used (such as non linear organic materials...). In that paper, the basic properties of integrated optic devices will outlined by giving typical examples in the two main present technologies : LiNb03 and semiconductors.