Tracking refers to the space between letters in a text in InDesign. The space between the letters can be increased or decreased depending on what you want for your design. To increase or decrease the space between the letters go to the type tool or double-click the text to enable the Type tool, with the type tool active, select all the letters. Go to the top menu bar and type the number for the space that you want between the letters. Type a positive number to increase the space or a negative number to decrease the space.