FSOC enables the transfer of data using optical carriers such as visible, infrared (IR), and ultraviolet (UV) light, without the need for physical medium. FSOC is commonly employed in Free-Space Optics (FSOC) to facilitate rapid data transmission between fixed locations over long distances. The wide optical bandwidth enables it to achieve higher data speeds compared to standard RF links. FSOC operates in the unlicensed spectrum above 300 GHz, which sets it apart from RF technology. This enables simple installation and robust security without being subject to regulatory limitations. The FSOC can be deployed where installing of fiber optics cable might be tough and may get costly. FSOC communications allow long-distance data transmission for scientific research projects and make satellite connections easier. Modulation is necessary to transmit baseband signals in communication networks. This enhances the effectiveness of the channel and reduces the occurrence of interference. OOK, PPM, BPSK, POLSK, OAM, OFDM, CSK and QAM are employed in FSOC. This system is explained below in this paper. These techniques enhance and optimize optical wireless communications