Spintronics is a new branch of condensed matter physics devoted to studies on the manipulation of the spin degree of freedom in solids. It involves spin polarization, spin dynamics, spin transport, and the detection of spin polarized electrons in metals and semiconductors. Spintronics has attracted great attention from scientists and manufacturers because of its potential application in information storage. A brief review of the development of spintronics and its most important discoveries will be given. The most exciting event in recent years may be the discovery of the giant magnetoresistance effect in metallic multilayer films and the successful application of this effect to information storage. Based on this effect, the magnetic recording density has been increased to 170 Gbit/in2. A magnetoresistive random access memory of 16 Mbit storage density has also been developed. These results clearly demonstrate the importance of spintronics for information technology.