To address the inherent bottlenecks of conventional solid and gas terahertz(THz) sources and detectors—such as limited bandwidth, susceptibility to material damage, and low optical-to-THz conversion efficiency—this paper systematically reviews the recent research progress in the generation and detection of THz waves via femtosecond laser excitation of liquid water and other liquid-phase media. The physical mechanisms underlying the stimulated THz emission from the liquid phase are thoroughly analyzed, with a comparative study on the radiation characteristics of two macroscopic fluid geometric configurations: the water film and the water line. The review highlights that under identical pump energy(e.g., 0.4 mJ) and focusing conditions, the peak THz electric field generated by the water line scheme is nearly 100 times stronger than that produced by air plasma. Furthermore, a broadband coherent detection scheme based on four-wave mixing in liquids is discussed in detail. By mitigating the limitations imposed by macroscopic lattice phonon absorption, this approach achieves ultra-broadband(>18 THz) and highly sensitive THz detection, surpassing gas-based detection methods by one to two orders of magnitude in sensitivity. Featuring the absence of a permanent material damage threshold and intrinsic broadband characteristics, liquid THz photonics offers a novel pathway to bridge the "THz gap". Despite the current challenges associated with high system complexity, liquid THz technology exhibits broad prospective applications in short-range high-resolution THz radar imaging, ultra-broadband spectral sensing, and strong-field nonlinear optics.