LiteBIRD is a forthcoming space mission dedicated to study the faint $B$-mode polarization patterns in the cosmic microwave background (CMB) that are believed to be the imprints of the gravitational waves from the period of cosmic inflation. The primary goal of the mission is the measurement of the tensor-to-scalar ratio $r$, with total uncertainty of $\delta r \sim 0.001$. LiteBIRD is planned to be launched in the 2030s to the Sun-Earth Lagrange point L2, where it will perform full-sky CMB measurements for three years. It will cover 15 frequency bands across the 34 to 448 GHz frequency range. The mission will also address key cosmological problems, including a measurement of the optical depth to reionization and constraints on the neutrino mass. With its advanced instrumentation, LiteBIRD will mitigate foreground contamination and systematic errors to provide high-fidelity data to improve our understanding of inflation, large-scale anomalies and other fundamental cosmological phenomena.