Mathematics - Mathematics is used throughout the world as an essential tool in many fields, including natural science, engineering, medicine, and the social sciences. Applied mathematics, the branch of mathematics concerned with application of mathematical knowledge to other fields, inspires and makes use of new mathematical discoveries and sometimes leads to the development of entirely new mathematical disciplines, such as statistics and game theory. Mathematicians also engage in pure mathematics, or mathematics for its own sake, without having any application in mind. There is no clear line separating pure and applied mathematics and practical applications for what began as pure mathematics are often discovered. (Wikipedia)
 

Some mathematical terms - click on any one above to Google.

• Why Do Math - showcases exciting mathematical and computational science topics
• Oregon University - What is Mathematics?
• Wales University, Centre for the Popularisation of Mathematics - The Methodology of Mathematics
• Paul's Online Math Notes - How to Study Mathematics
• Beauty of Mathematics from Parachutes on Vimeo:  

  "Mathematics, rightly viewed, possesses not only truth, but supreme beauty — a beauty cold and austere, without the gorgeous trappings of painting or music." —Bertrand Russell

• "That's Mathematics" by Tom Lehrer the American singer-songwriter, satirist, pianist - and mathematician

  Mathematics - Open Textbooks  
Links to open access (free) textbooks.

• Online Mathematics Textbooks - George Cain's Place - School of Mathematics, Georgia Institute of Technology, Atlanta, Georgia
• OpenTextBookStore - mathematics
• Wikibooks:Mathematics bookshelf - from Wikibooks, the open-content textbooks collection
• FreeTechBooks - Mathematics - freely available books hosted on websites that belong to the authors or the publishers
• AMS Books Online - Links to Mathematics Books Online
• Open Library - keyword "mathematics"
• Edu Technology and Algebra - Open and Online Mathematics Textbooks

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

• Physics Forums - Math & Science Learning Materials
• WolframAlpha Blog - interactive guide step by step through process of solving mathematical problems
• Mathematics Stack Exchange - question and answer site for people studying math at any level and professionals in related fields
• Drexel University -The Math Forum
• MHF - Math Help Forum
• planetmath.org - virtual community which aims to help make mathematical knowledge more accessible
• Science Forums - mathematics

See Also:
Massive Open Online Courses (MOOCs)

  Mathematics - Best Resource Sites  
iBerry's choice - other recommendations welcome!

• American Mathematical Society (AMS) (US) - furthers mathematical research and scholarship through programs and services that promote mathematical research and its uses
• Applied Math and Science Education Repository (AMSER) - portal of educational resources and services
• MERLOT II - Mathematics Portal
• Wisconsin University (US) - Catalog of Mathematics Resources on the Web