  The identity of dark matter is one of the key outstanding problems in both
particle and astrophysics. In this thesis, I review some candidates of dark
matter, especially WIMPs (weakly interacting massive particles) which is one of
the best candidate so it is called that WIMPs miracle. In addition of this,
there are also some theories of modification of gravity, by changing the law of
gravity, it could be possible that the dark matter observations are explained.
Until the dark matter particle is detected, there is some room for uncertainty.
So we should consider every part of the problem and solve it. Dark matter
problem is covering a large area so every possibility is important. So f(R)
gravity is also reviewed in this thesis and some theories are considered as a
possible solution of dark matter problem. Finally we highlight that, even in
the case of WIMPs or another particles solution, f(R) gravity is also can be
used for this problem. However, last words will be said by experiments.
