Mathematics
Q&A for people studying math at any level and professionals in related fields
TeX - LaTeX
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems
Meta Stack Overflow
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Area 51
Stack Exchange Network staging zone, where users come together to build new Q&A sites
Writers
Q&A for authors, editors, reviewers, professional writers, and aspiring writers
Academia
Q&A for academics and those enrolled in higher education
Programmers
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Computer Science
Q&A for students, researchers and practitioners of computer science
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Physics
Q&A for active researchers, academics and students of physics
Cross Validated
Q&A for statisticians, data analysts, data miners and data visualization experts
Game Development
Q&A for professional and independent game developers
Database Administrators
Q&A for database professionals who wish to improve their database skills and learn from others in the community
Theoretical Computer Science
Q&A for theoretical computer scientists and researchers in related fields
Electrical Engineering
Q&A for electronics and electrical engineering professionals, students, and enthusiasts
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems.
Server Fault
Q&A for professional system and network administrators
German Language & Usage
Q&A for speakers of German wanting to discuss the finer points of the language and translation
Personal Productivity
Q&A for people wanting to improve their personal productivity
Parenting
Q&A for parents, grandparents, nannies and others with a parenting role
Cryptography
Q&A for software developers, mathematicians and others interested in cryptography
Computational Science
Q&A for scientists using computers to solve scientific problems
Ask Patents
Q&A for people interested in improving and participating in the patent system
Physical Fitness
Q&A for physical fitness professionals, athletes, trainers, and those providing health-related needs