Stack Overflow
Q&A for professional and enthusiast programmers
Super User
Q&A for computer enthusiasts and power users
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems
Arqade
Q&A for passionate videogamers on all platforms
Mathematics
Q&A for people studying math at any level and professionals in related fields
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
The Workplace
Q&A for members of the workforce navigating the professional setting
Vi and Vim
Q&A for people using the vi and Vim families of text editors
English Language Learners
Q&A for speakers of other languages learning English
User Experience
Q&A for user experience researchers and experts
Russian Language
Q&A for students, teachers, and linguists wanting to discuss the finer points of the Russian language
Software Engineering
Q&A for professionals, academics, and students working within the systems development life cycle
Ethereum
Q&A for users of Ethereum, the decentralized application platform and smart contract enabled blockchain
Stack Apps
Q&A for apps, scripts, and development with the Stack Exchange API
Game Development
Q&A for professional and independent game developers
Server Fault
Q&A for system and network administrators
Ask Different
Q&A for power users of Apple hardware and software
Medical Sciences
Q&A for professionals in medical and allied health fields, students of those professions, related academics, and others with a sound understanding of medicine and healthcare-related sciences