Stack Overflow
Q&A for professional and enthusiast programmers
Aviation
Q&A for aircraft pilots, mechanics, and enthusiasts
Cross Validated
Q&A for people interested in statistics, machine learning, data analysis, data mining, and data visualization
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
TeX - LaTeX
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems
Ask Different
Q&A for power users of Apple hardware and software
Mathematics
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Meta Stack Exchange
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Data Science
Q&A for Data science professionals, Machine Learning specialists, and those interested in learning more about the field
Stack Apps
Q&A for apps, scripts, and development with the Stack Exchange API
Open Data
Q&A for developers and researchers interested in open data