Stack Overflow
Q&A for professional and enthusiast programmers
Cross Validated
Q&A for people interested in statistics, machine learning, data analysis, data mining, and data visualization
Bicycles
Q&A for people who build and repair bicycles, people who train cycling, or commute on bicycles
Writing
Q&A for the craft of professional writing, including fiction, non-fiction, technical, scholarly, and commercial writing
Physical Fitness
Q&A for physical fitness professionals, athletes, trainers, and those providing health-related needs
German Language
Q&A for speakers of German wanting to discuss the finer points of the language and translation
Personal Finance & Money
Q&A for people who want to be financially literate
Mathematics
Q&A for people studying math at any level and professionals in related fields
Philosophy
Q&A for those interested in the study of the fundamental nature of knowledge, reality, and existence
Home Improvement
Q&A for contractors and serious DIYers
Data Science
Q&A for Data science professionals, Machine Learning specialists, and those interested in learning more about the field
The Great Outdoors
Q&A for people who love being outdoors enjoying nature and wilderness, and learning about the required skills and equipment
Worldbuilding
Q&A for writers/artists using science, geography and culture to construct imaginary worlds and settings
Web Applications
Q&A for power users of web applications
Super User
Q&A for computer enthusiasts and power users
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
Puzzling
Q&A for those who create, solve, and study puzzles