Kerning is the space between letters in words.
Emphasis is the exaggeration of words or a aspect of a design in a text or design with a different style to have words or aspect stand out.
Descender is a part of a letter that extends below the level of the base of a letter such as a g or a y.
Visual Impact is the first thing we work toward in a design. Also it is an aspect of a design that has a strong effect, visually.
Constraint(s) refers to some limitation on the conditions under which a system is developed, or on the requirements of the system.