Radia Perlman's specialties include network routing protocols and network security. She developed the technology for making network routing self-stabilizing, largely self-managing, and scalable. She also invented the spanning tree algorithm, which transformed Ethernet from a technology that supported a few hundred nodes within a single building, to something that could support large networks. The specific routing protocol she designed (IS-IS) is still widely deployed, and the concepts have been copied into other link state protocols such as OSPF. Her spanning tree protocol also continues to be widely deployed, and is the technology behind modern-day Ethernet. She is the author of the textbook “Interconnections” (about network layers 2 and 3) and coauthor of “Network Security: Private Communication in a Public World” (about cryptography, quantum computing, quantum-safe public key algorithms, and more). She has taught as adjunct faculty at various universities including MIT, Harvard, University of Washington, and Texas A&M. She holds S.B. and S.M. in mathematics, and a PhD in computer science, all from MIT.