Kerning
Kerning is a method that adjusts the spacing between two letters or characters in a word if the font makes a certain letter appear too far away from or too close to another. If letters are too close, they may blend together, which can make them difficult to read.
Tracking
Tracking is a similar process to kerning that focuses on the spacing between all letters in a word, rather than just a few letters in a word. Tracking is usually uniform, meaning you apply an equal amount of space between each letter so that it doesn't look too spaced out or too tight.
Leading
Leading is the spacing between multiple lines of text. If lines of text have spaces between them that are too large, it can affect the overall flow of the text for the reader. Leading can make a significant difference in the text, so it's best to use it in moderation. Leading comes from an outdated process of inserting lead pieces between text blocks when typesetting. Today, you can use a number of computer programs to complete leading, giving you the proper amount of spacing between lines of text.
https://www.indeed.com/career-advice/career-development/kerning-vs-tracking-vs-leading