光照上网技术（又称灯光上网技术，英语：Li-Fi，英文全称：Light Fidelity），是利用可见光通讯技术（VLC）来实现互联网的信息传输。通俗地讲，光照上网技术就是以各种可见光源作为信号发射源，通过控制器控制灯光的通断，从而控制光源和终端接收器之间的通讯。它具有高带宽（其带宽是WIFI的1万倍）、高安全性（室内电脑、移动终端信息不会泄露到室外）、节能等特点。尽管Li-Fi灯泡必须保持打开状态才能传输数据，但是灯泡可以调暗至人眼看不到的程度，却仍然能够运行。

Light Fidelity (Li-Fi) is a bidirectional, high speed and fully networked wireless communication technology similar to Wi-Fi. The term was coined by Harald Haas and is a form of visible light communication and a subset of optical wireless communications (OWC) and could be a complement to RF communication (Wi-Fi or Cellular network), or even a replacement in contexts of data broadcasting. It is so far measured to be about 100 times faster than some Wi-Fi implementations, reaching speeds of 224 gigabits per second.