Abstract: The detection of TeV and GeV gamma rays from galactic and extragalactic sources is an important step forward in understanding the sites of production and acceleration of cosmic rays (CRs) including what types of CRs are produced and how they are accelerated to very high energies. Gamma rays are not deflected by the interstellar and intergalactic magnetic fields nor absorbed by the interstellar gas and dust. Therefore, gamma rays can be detected, both at GeV energies by space-borne instruments, such as NASA's Fermi Gamma-ray Space Telescope, and at TeV energies by ground-based instruments, like the imaging atmospheric Cherenkov telescopes (IACTs). In the Galaxy, a wide range of gamma-ray sources, such as supernova remnants, pulsars and pulsar wind nebulae, gamma-ray binaries, and star-forming regions are candidate sites of production and acceleration of cosmic rays. Additionally, the angular and spectral distribution of the diffuse galactic gamma-ray emission caused by the CRs interacting with molecular clouds can provide unique information about the character of propagation of CRs in galactic magnetic fields. In this presentation, I want to talk about the gamma-ray and radio detection of the supernova remnants and molecular clouds, and finding their associated counterparts in other wavelengths to better understand the nature of the CR accelerators and their interactions with the surrounding environment.