  The current standard cosmological model is constructed within the framework
of general relativity with a cosmological constant $\Lambda$, which is often
associated with dark energy, and phenomenologically explains the accelerated
cosmic expansion. Understanding the nature of dark energy is one of the most
appealing questions in achieving a self-consistent physical model at
cosmological scales. Modification of general relativity could potentially
provide a more natural and physical solution to the accelerated expansion. The
growth of the cosmic structure is sensitive in constraining gravity models. In
this paper, we aim to provide a concise introductory review of modified gravity
models from an observational point of view. We will discuss various mainstream
cosmological observables, and their potential advantages and limitations as
probes of gravity models.
