Stack Overflow
Q&A for professional and enthusiast programmers
Super User
Q&A for computer enthusiasts and power users
Cross Validated
Q&A for people interested in statistics, machine learning, data analysis, data mining, and data visualization
Data Science
Q&A for Data science professionals, Machine Learning specialists, and those interested in learning more about the field
English Language Learners
Q&A for speakers of other languages learning English
Arqade
Q&A for passionate videogamers on all platforms
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems
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Area 51
Q&A for proposing new sites in the Stack Exchange network
Software Engineering
Q&A for professionals, academics, and students working within the systems development life cycle
Artificial Intelligence
Q&A for people interested in conceptual questions about life and challenges in a world where "cognitive" functions can be mimicked in purely digital environment
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Chinese Language
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Computer Science
Q&A for students, researchers and practitioners of computer science
Personal Finance & Money
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Code Golf
Q&A for programming puzzle enthusiasts and code golfers
Ask Ubuntu
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Mathematics
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Information Security
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Video Production
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MathOverflow
Q&A for professional mathematicians
Quantitative Finance
Q&A for finance professionals and academics
Chess
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Open Source
Q&A for people organizing, marketing or licensing open source development projects
Vi and Vim
Q&A for people using the vi and Vim families of text editors
Writing
Q&A for the craft of professional writing, including fiction, non-fiction, technical, scholarly, and commercial writing
Computational Science
Q&A for scientists using computers to solve scientific problems
Beer, Wine & Spirits
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Cryptography
Q&A for software developers, mathematicians and others interested in cryptography
Board & Card Games
Q&A for people who like playing board games, designing board games or modifying the rules of existing board games
Code Review
Q&A for peer programmer code reviews
Server Fault
Q&A for system and network administrators
Web Applications
Q&A for power users of web applications
Meta Stack Exchange
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
User Experience
Q&A for user experience researchers and experts
TeX - LaTeX
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems
Theoretical Computer Science
Q&A for theoretical computer scientists and researchers in related fields
Open Data
Q&A for developers and researchers interested in open data