Flexible antennas are key components in modern wireless systems, valued for their lightweight design, adaptability, and integration with non-planar surfaces. They are categorized into four main types: conformal antennas, which adapt to curved structures for aerodynamic and stealth uses; wearable or textile antennas, integrated into clothing or body-worn devices for healthcare, military, and sports; reconfigurable antennas, which dynamically adjust frequency, radiation pattern, or polarization; and fluidic or movable architectures, utilizing liquid metals or mechanical actuation for tunability and shape adaptability. Material selection significantly influences both mechanical flexibility and electromagnetic performance. Traditional conductors like copper and silver offer high conductivity but require special techniques for flexibility. Conductive polymers and composites combine electrical performance with mechanical compliance and environmental resistance. Textile-based conductors integrate antennas directly into fabrics for comfort and durability. Advanced flexible substrates such as polyimide, PDMS, LCP, and TPU provide low dielectric loss and resilience under stress. This review outlines classification, materials, and fabrication advances, emphasizing their role in enabling next-generation communication technologies like 5G/6G, IoT devices, aerospace systems, and wearable healthcare solutions. Flexible antennas promise compact, unobtrusive, and high-performance wireless connectivity for future applications