RGB, CMYK, Fills & Strokes. and Paths

There are two different color modes for Web and for print: RGB, or Red, Green and Blue. This is the color mode used for the Web, TVs, computer monitors and mobile devices. CMYK is the color mode for print materials. It consists of Cyan, Magenta, Yellow, and Black (the "k" is used instead of "b" since "b" is used for Blue in the Web color mode). When these colors are combined in various combinations, they can display all colors in the spectrum. Some who have trouble remembering the difference can think of it as: there are three letters in "web" and there are three colors that make up the Web color mode, RGB. There are more letters in the word "print", just as there are more colors in the Print color mode, CMYK.
Fill color is the area inside the path, or the color on the inside boundaries of the shape; stroke color refers to the line that is on the outside the object (letters, shapes). If either the fill or stroke is represented by a white box with a red line through it, it means that element has no color. Changing the colors of either or both is easy in Illustrator, and Adobe gives at least three different ways to do it. First is at the bottom of the toolbar, under the magnifying glass tool and the hand tool. The first box is the fill color; the second box without the center is the stroke color. The second option for finding fill and stroke color is near the top of the screen, just under the Menu Bar. The first box represents the fill color; the second box for the stroke color is just like the bottom of the Tool Bar, only smaller. The third option is within the Color Panel.
Paths are essential to creating any artwork in Illustrator from basic lines and shapes to vector portraits.  They are the "bones" upon which everything else that is created sits to comprise the artwork. Within those paths are anchor points, or the joints or building blocks that hold the paths together; they tell the paths where to go. For curved paths, the points have control handles that tell the path how to curve up or down. Paths can be open or closed. Closed paths are simply paths that have no open ends, like shapes. Open paths are paths that are not closed; there is nothing connecting it, like a straight and arched lines or spirals.
To join two paths, instead of using the Pathfinder or Compound  Shape tools, the Join or Average Commands can be time savers and one may work better that the other, depending on the project. By selecting the two anchor points and choosing the Object Menu, then Path, then Average or Join
Splitting paths can be done with either the Scissors and Knife tool. The Scissors tool splits paths based on selected anchor points. It is as easy as clicking on an object's anchor point with the Direct Select tool and selecting another anchor point on the same object. The Knife tool acts like a liquid knife, and does not cut in a straight line unless the Alt or Option key is pressed and held down until releasing the mouse.