Stack Overflow
Q&A for professional and enthusiast programmers
Science Fiction & Fantasy
Q&A for science fiction and fantasy enthusiasts
Music: Practice & Theory
Q&A for musicians, students, and enthusiasts
Meta Stack Exchange
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Super User
Q&A for computer enthusiasts and power users
Language Learning
Q&A for students, teachers, polyglots, and anyone interested in the techniques of second-language acquisition
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems
Ask Different
Q&A for power users of Apple hardware and software
Genealogy & Family History
Q&A for expert genealogists and people interested in genealogy or family history
English Language Learners
Q&A for speakers of other languages learning English
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Movies & TV
Q&A for movie and TV enthusiasts
History
Q&A for historians and history buffs
Physics
Q&A for active researchers, academics and students of physics
Software Engineering
Q&A for professionals, academics, and students working within the systems development life cycle
Information Security
Q&A for information security professionals
Quantum Computing
Q&A for engineers, scientists, programmers, and computing professionals interested in quantum computing
Code Golf
Q&A for programming puzzle enthusiasts and code golfers
Portuguese Language
Q&A for linguists, teachers and learners wanting to discuss the finer points of the Portuguese language
Server Fault
Q&A for system and network administrators
Ask Ubuntu
Q&A for Ubuntu users and developers
Travel
Q&A for road warriors and seasoned travelers