Sparkfun Electricity Tutorial: This tutorial goes through the basics of what electricity is, then links you to further lessons about electrical power and circuits.
All About Circuits: A series of online textbook chapters that take you through all aspects of electricity.
Electricity for Kids: A fun, interactive site for kids to learn the basics of electricity through games and quizzes.
Siemens Basics of Electricity: An online course designed to train Siemens engineers. Siemens has many similar courses on other aspects of electrical engineering as well.
These resources teach coding in general. Arduino programs are written in Wiring (based on Processing), which is similar to the C++ programming language. For Arduino-specific tutorials, check the Arduino section.
Codecademy: You can use Codecademy's tutorials to learn multiple programming languages, including Java, HTML/CSS, Javascript, and more.
Code.org: Fun tutorials that teach kids the basics of coding using Angry Birds and Plants vs. Zombies.
Treehouse: Similar to Codecademy, but with more depth and languages included - tutorials cost money.
Udemy: An "online learning marketplace" - collection of code courses, some paid, some free.
Scratch: One of the most popular resources for beginners - teaches coding through drag-and-drop tutorials.
Code Avengers: Similar to Codecademy, but you get to be called an avenger!
Girl Develop It: Helps women find coding workshops and classes in their area.
Learn About Electronics: Collection of articles about various electronics, electricity, and circuits.
Sparkfun Breadboard Tutorial: This page covers the basics of breadboards, but links on the button send you to component-specific articles to broaden your knowledge.