Structural health monitoring (SHM) signifies a framework with the capacity to identify and translate unfriendly “changes” in a structure so as to enhance dependability and lessen life-cycle costs. The best test in outlining an SHM framework is comprehending what “changes” to search for and how to recognize them. Composite materials have displayed extra difficulties for support and repair over metallic parts because of the anisotropy of the material. Often shortened to “composites," or called “composition materials," these are engineered or naturally occurring materials made from two or more constituent materials with significantly different physical or chemical properties that remain separate and distinct at the macroscopic scale within the finished structure. The composite is made of two materials, in which one of the materials, called the reinforcing phase, is in the form of fibers, sheets, or particles, and is embedded in the other material, called the matrix phase. The reinforcing material and the matrix material can be metal, ceramic, or polymer. Composites are used because overall properties of the composites are superior to those of the individual components. Basically there are three different types of composites, namely: particle-reinforced composites, fiber-reinforced composites, and structural composites. Particles are used to increase the modulus of the matrix, to decrease the permeability of the matrix, to decrease the ductility of the matrix, and also to produce inexpensive composites. Fiber-reinforced composites are made of: metals, ceramics, glasses, or polymers that have been turned into graphite and are known as carbon fibers. Fibers increase the modulus of the matrix material. A structural composite consists of both homogeneous and composite materials. This chapter presents the major applications of composite materials such as polymer-matrix, cement-matrix, carbon-matrix, metal-matrix, and ceramic-matrix. Also this chapter presents composite materials’ properties, including mechanical, thermal, and durability of various applications. © 2019 Elsevier Ltd. All rights reserved.