The article reviews the theoretical and experimental status of quantum repeaters based on atomic ensembles and linear optics. Quantum repeaters are essential for distributing quantum states over long distances, which is limited by photon loss. The no-cloning theorem prevents classical amplification methods from being used in quantum communication. Quantum repeater protocols, which create long-distance entanglement from shorter-distance entanglement via entanglement swapping, offer a solution. These protocols require the ability to create entanglement heraldedly, store it in quantum memories, and perform entanglement swapping. Atomic ensembles, combined with linear optical techniques and photon counting, are a promising strategy for realizing quantum repeaters. The article compares different approaches quantitatively, focusing on outperforming direct photon transmission. It discusses the DLCZ protocol, improvements such as entanglement swapping via two-photon detections, and multiplexing techniques. The performance of different protocols is compared, considering entanglement distribution time and robustness. Experimental implementations of various protocols are reviewed, including the creation and swapping of entanglement, quantum light sources, quantum memories, detectors, and quantum channels. The article concludes with a discussion of other approaches to quantum repeaters and future prospects.The article reviews the theoretical and experimental status of quantum repeaters based on atomic ensembles and linear optics. Quantum repeaters are essential for distributing quantum states over long distances, which is limited by photon loss. The no-cloning theorem prevents classical amplification methods from being used in quantum communication. Quantum repeater protocols, which create long-distance entanglement from shorter-distance entanglement via entanglement swapping, offer a solution. These protocols require the ability to create entanglement heraldedly, store it in quantum memories, and perform entanglement swapping. Atomic ensembles, combined with linear optical techniques and photon counting, are a promising strategy for realizing quantum repeaters. The article compares different approaches quantitatively, focusing on outperforming direct photon transmission. It discusses the DLCZ protocol, improvements such as entanglement swapping via two-photon detections, and multiplexing techniques. The performance of different protocols is compared, considering entanglement distribution time and robustness. Experimental implementations of various protocols are reviewed, including the creation and swapping of entanglement, quantum light sources, quantum memories, detectors, and quantum channels. The article concludes with a discussion of other approaches to quantum repeaters and future prospects.