Fiber Bragg Gratings (FBGs) are essential optical devices that reflect specific wavelengths of light, enabling precise sensing and filtering in industries like telecommunications, aerospace, and structural health monitoring. In this paper, the main writing methods of MCF FBGs and their sensing. This SPIE Tutorial Text excerpt discusses the usefulness and versatlity of fiber Bragg gratings. FBGs are highly valued for their compact design, high sensitivity, and. Abstract: In this paper, the brief introduction of Fiber Bragg Grating, its significant applications, sensing principles, properties, fabrication and the basic designing of FBG have been discussed. FBG's are relatively simple to manufacture, small in dimension, low cost and exhibits good immunity.