This work provides a comprehensive study on LED-based Visible Light Communications (VLC), an emerging wireless technology that leverages the high-speed switching capabilities of Light Emitting Diodes for data transmission. VLC offers significant advantages, including license-free spectrum, immunity to electromagnetic interference (EMI), and enhanced physical-layer security. The study delves into the core system architecture, covering advanced modulation formats (such as OFDM), high-sensitivity photodetector reception, and signal processing algorithms for complex optical channels. Furthermore, the practical potential of VLC in indoor high-precision positioning, underwater wireless communication, and EMI-sensitive environments (e.g., hospitals) is analyzed. Experimental and simulation results demonstrate that by optimizing driver circuits and equalization techniques, LED-based VLC systems can achieve Gbps-level data rates, offering a promising solution to mitigate the spectrum scarcity in future wireless networks.