This white paper explains how a next-generation IETF internet-protocol innovation called “L4S”, pioneered by Nokia Bell Labs, can be used to control and reduce the latency that users experience on the internet. L4S significantly improves end-to-end latency by tackling queuing latency, which is the single biggest – and most often overlooked – source of latency. Queuing latency is caused by packets waiting in buffers before being forwarded. The IETF published the L4S RFCs in January 2023. This paper describes the fundamental components of L4S and outlines a path for end-to-end support in communications service provider (CSP) networks.