Orthogonal Frequency-Division Multiple Access (OFDMA) is a digital communication method that allows multiple users to share the same frequency channel simultaneously. It divides the available bandwidth into many smaller sub-channels, each assigned to different users. This efficient use of spectrum helps improve data transmission rates and reduces interference. In OFDMA, each user transmits data over their assigned sub-channels, which are orthogonal to each other. This means that the signals do not interfere, allowing for clearer communication. OFDMA is widely used in modern wireless technologies, including 4G and 5G networks, enhancing overall network performance.