In this paper, we comprehensively review the progress in the development of HCFs including fiber design, fabrication and parameters (with comparisons to conventional single-mode fibers) and support technologies like splicing and testing. Hollow-core optical fibers (HCFs) have unique properties like low latency, negligible optical nonlinearity, wide low-loss spectrum, up to 2100 nm, the ability to carry high power, and potentially lower loss then solid-core single-mode fibers (SMFs). It explores the diverse light-guiding mechanisms employed, including photonic. For decades, optical fibers have relied on a solid glass core to guide light and have formed the backbone of global telecommunications. However, glass imposes a fundamental physical limitation because light travels through it approximately 30 percent slower than through air.
