Aviation
Q&A for aircraft pilots, mechanics, and enthusiasts
Retrocomputing
Q&A for vintage-computer hobbyists interested in restoring, preserving, and using the classic computer and gaming systems of yesteryear
Meta Stack Exchange
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Super User
Q&A for computer enthusiasts and power users
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems
Stack Overflow
Q&A for professional and enthusiast programmers
Software Recommendations
Q&A for people seeking specific software recommendations
Server Fault
Q&A for system and network administrators
Space Exploration
Q&A for spacecraft operators, scientists, engineers, and enthusiasts
Mathematics
Q&A for people studying math at any level and professionals in related fields
Computer Graphics
Q&A for computer graphics researchers and programmers
Astronomy
Q&A for astronomers and astrophysicists
Game Development
Q&A for professional and independent game developers
Physics
Q&A for active researchers, academics and students of physics
Electrical Engineering
Q&A for electronics and electrical engineering professionals, students, and enthusiasts
Arduino
Q&A for developers of open-source hardware and software that is compatible with Arduino