Science

• Science (general)
• Open Courseware (OCW)
   
  • Chemistry
  • Open Courseware (OCW)
     
  • Physics
  • Open Courseware (OCW)
  • Applied Physics (OCW)

Physics: science of matter and its motion, as well as space and time, deals with concepts such as force, energy, mass, and charge (Wikipedia).

• American Physical Society (APS) Why Study Physics? - Physics is crucial to understanding the world around us, the world inside us, and the world beyond us. It is the most basic and fundamental science
• OpenStax CNX, What is physics? - physics is defined as that branch of science which studies natural phenomena in terms of basic laws and physical quantities
• physics.org, What is physics? - physics is about asking fundamental questions and trying to answer them by observing and experimenting

• collegeopentextbooks.org - Open Textbooks: Physics
• E-Books Directory, Free Physics Books - 500 online physics books available for free download; classical mechanics, thermodynamics, electromagnetism, optics, quantum physics, atomic and nuclear physics, astrophysics
• FreeBookCentre.net, Physics eBooks - free e-books and guides, some viewed online, some downloadable
• LightandMatter.com - books (free): Light & Matter; Simple Nature; Mechanics; Conceptual Physics; Calculus; General Relativity
• Physics Database, Free Physics Books - over 100 free physics book

  Physics - Support for Learners  
Sites that actively support learners - eg learner communities, forums, expert help etc

• FQXi Forum - specialists and non-specialists alike can discuss anything concerning foundational questions in physics, cosmology, and related fields
• The Physics Forum - FAQ, community, today's posts
• Physics Forums - provides community for people (whether students, professional scientists, or hobbyists) to learn and discuss science; forums, videos, insights
• Physics Help Forum
• reddit Physics - aim to build a subreddit frequented by physicists, scientists and those with a passion for physics
• ScienceForums.Net, Modern and Theoretical Physics - Atomic structure, nuclear physics, etc

See Also:
Massive Open Online Courses (MOOCs)

  Best resource sites  
iBerry's choice - recommendations welcome!

• Institute of Physics (UK) - scientific charity devoted to increasing the practice, understanding and application of physics: Events, Publications, Education, Activities, Careers, Resources
• PhysLINK (US), Physics & Astronomy online Education & Reference - research & reference, meeting place for professionals, students & others
• Wikipedia - The Physics Portal

• ComPADRE (US) - network of free online resource collections in Physics and Astronomy
• European Physical Society (EPS) - not for profit association promoting physics and physicists in Europe
• Illinois University (US) - Nano, Quantum & Statistical Mechanics & Thermodynamics Educational Sites
• Lawrence Berkeley National Laboratory (LBNL) (US), The Particle Adventure - interactive tour of quarks, neutrinos, antimatter, particle detectors, extra dimensions, dark matter, accelerator
• MERLOT/Physics Teaching and Learning (US) - resources for instructors and students of physics; focuses on open access and open source content that improves conceptual understanding and problem solving
• PhysOrg.com (US) - web-based science, research and technology news service
• physics.org (UK) - database of over 4,000 handpicked physics sites; features and commonly asked questions; games; experiments; advice and information about studying physics and careers
• Polish Academy of Sciences (PL), Physics Journals - comprehensive links listing
• scienceworld.wolfram.com (US), Physics - public service for scientific knowledge and education
• Virtual Library: Physics