This paper presents a review of fiber optic-based sensors and their main characteristics and classification. In the same way, the paper includes a series of applications of sensors based on fiber optics with Bragg gratings in different fields of study in research such as medicine, civil engineering, communications engineering, chemistry, and biochemistry, among others. Such sensors are developed taking advantage of certain characteristics of optical fibers, such as photosensitivity and the variation of the refractive index of their core.  Applications of fiber optics in the detection of telecommunications signals are also discussed, particularly as a filter device through the usage of Bragg gratings. Due to its versatility, these optical devices have provided promising results and have become a leading technology in next generation DWDM systems, as well as in optical sensing networks.