Each element has two areas that color can be applied to: the fill, which is the inside, and the stroke, which is the border. Fill and Stroke colors can be adjusted in the Options bar when the element, such as text or a shape, is selected.

To choose a color, double-click the Fill or Stroke from the Options bar. The Color Picker will open (see below for details). Alternatively, click the arrow next to the Fill or Stroke to open a panel of Swatches and select a color. The white box with a red line through it indicates transparency.

To change the thickness of the Stroke, click the drop-down to the right of the Fill and Stroke in the Options bar. Alternatively, click to open the Stroke panel to the right of the interface (if it isnt available, navigate to Window > Stroke). The pattern of the Stroke can be adjusted here too.

The Color Picker has many options for finding the right colors. The most obvious is the visual method on the left side of the pop-up. To choose a color visually, click around the large square and drag the meter on the right up and down to alter the available colors. When a color is clicked on, the numbers on the right side will change. These numbers indicate the colors code in various color spaces. 

When creating an InDesign Document, the color code (RGB, CMYK) will be set according to the intent. When a Print preset is selected, CMYK colors will be used. When Intent: Web is selected, RGB colors will be used. If a document is printed and the print colors look significantly different than the colors on the screen do, it may be the result of an incorrect setting in InDesignor it may be the result of a faulty printer!

RGB stands for red, green, and blue, and represents how colors are coded for digital screens. Every color visible on a screen is made up of a combination of red, green, and blue, and altering these numbers (from 0-255) changes the intensity of that aspect of a color. For instance, a pure blue would be R: 0, G: 0, B: 255no red or green, full blue.

CMYK stands for cyan, magenta, yellow, and key (which is black). This color set may be familliar to anyone who has changed color cartridges in a printer before. Any color thats printed is made of these four colors, with intensities measured in percentage. 

Hexidecimal codes, usually called hex codes, present colors as a string of either 3 or 6 numbers (0-9) or letters (A-F), marked with a # symbol. The hex code is visible in the bottom-right corner of the Color Picker. Similar to RGB, this code marks colors meant for a screen, but is used in coding and website design rather than document design. Most current browsers can read both color codes, but hex codes are recommended for projects that will be exported as HTML.

Color swatches can be used to save a color and quickly apply it to elements. This is especially useful when working with a color theme or palette because it will save time when applying colors through the document. Swatches are accessible in the drop-down menu for both Fill and Stroke.

To save a color as a swatch, open the Color Picker (double-click the Fill or Stroke color from the Options bar) and select the desired color. Then, click Add Swatch. The color will apply to the selected element, and be added to the swatches list for later use at any time.