Mathematics
Q&A for people studying math at any level and professionals in related fields
Stack Overflow
Q&A for professional and enthusiast programmers
Electrical Engineering
Q&A for electronics and electrical engineering professionals, students, and enthusiasts
Chemistry
Q&A for scientists, academics, teachers and students
Programmers
Q&A for professional programmers interested in conceptual questions about software development
Meta Stack Overflow
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Theoretical Computer Science
Q&A for theoretical computer scientists and researchers in related fields
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems.
Physics
Q&A for active researchers, academics and students of physics
Server Fault
Q&A for professional system and network administrators
Database Administrators
Q&A for database professionals who wish to improve their database skills and learn from others in the community
Raspberry Pi
Q&A for users and developers of hardware and software for Raspberry Pi
Programming Puzzles & Code Golf
Q&A for programming puzzle enthusiasts and code golfers
Cryptography
Q&A for software developers, mathematicians and others interested in cryptography
Biology
Q&A for biology researchers, academics, and students
Computational Science
Q&A for scientists using computers to solve scientific problems