Stack Overflow
Q&A for professional and enthusiast programmers
Mathematics
Q&A for people studying math at any level and professionals in related fields
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems
Cryptography
Q&A for software developers, mathematicians and others interested in cryptography
Code Golf
Q&A for programming puzzle enthusiasts and code golfers
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
Travel
Q&A for road warriors and seasoned travelers
Super User
Q&A for computer enthusiasts and power users
Area 51
Q&A for proposing new sites in the Stack Exchange network
TeX - LaTeX
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems
Philosophy
Q&A for those interested in the study of the fundamental nature of knowledge, reality, and existence
Data Science
Q&A for Data science professionals, Machine Learning specialists, and those interested in learning more about the field
Android Enthusiasts
Q&A for enthusiasts and power users of the Android operating system
Physics
Q&A for active researchers, academics and students of physics
Signal Processing
Q&A for practitioners of the art and science of signal, image and video processing
History
Q&A for historians and history buffs
Bicycles
Q&A for people who build and repair bicycles, people who train cycling, or commute on bicycles
Server Fault
Q&A for system and network administrators
Vi and Vim
Q&A for people using the vi and Vim families of text editors
Law
Q&A for legal professionals, students, and others with experience or interest in law
Puzzling
Q&A for those who create, solve, and study puzzles
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Software Engineering
Q&A for professionals, academics, and students working within the systems development life cycle
Politics
Q&A for people interested in governments, policies, and political processes
Aviation
Q&A for aircraft pilots, mechanics, and enthusiasts
Worldbuilding
Q&A for writers/artists using science, geography and culture to construct imaginary worlds and settings
Linguistics
Q&A for professional linguists and others with an interest in linguistic research and theory
Academia
Q&A for academics and those enrolled in higher education
Code Review
Q&A for peer programmer code reviews
Stack Apps
Q&A for apps, scripts, and development with the Stack Exchange API
Electrical Engineering
Q&A for electronics and electrical engineering professionals, students, and enthusiasts
Computational Science
Q&A for scientists using computers to solve scientific problems
Computer Science
Q&A for students, researchers and practitioners of computer science
Skeptics
Q&A for scientific skepticism
Theoretical Computer Science
Q&A for theoretical computer scientists and researchers in related fields
Information Security
Q&A for information security professionals
Cross Validated
Q&A for people interested in statistics, machine learning, data analysis, data mining, and data visualization
Psychology & Neuroscience
Q&A for practitioners, researchers, and students in cognitive science, psychology, neuroscience, and psychiatry
Biology
Q&A for biology researchers, academics, and students
Constructed Languages
Q&A for designers and users of artificial or invented languages, consciously developed instead of having developed naturally