Glass fibers feature extremely low thermal conductivity, high modulus, high toughness, light weight and non-combustible property. These materials can work in situations in which plastics and metals would fail and need to be part of designer’s repertoire. They have many applications in design engineering and can solve many special problems. This paper contains a number of chapters as follows: introduction to glass fibers, manufacturing processes of glass fibers, markets and applications of glass fibers. The conclusion of this paper contains some strategic lines of glass fibers usage in industry and estimations about the future development of glass fibers.