HTML

A PNG (Portable Network Graphics) file is a bitmap image format that has been designed to store images with an alpha channel. This format is primarily used for transparency so that it can be placed over other graphics in many design applications.

A prediction model used in human-computer interaction. It states that the time required to move to a target area rapidly increases as the distance to the target increases. The law was proposed by Paul Fitts, an American psychologist, in 1954 as a mathematical model of movement with limited cognitive capacity.

Fitts hypothesized that one would quickly select its first apparent target when reaching for an object before considering alternatives — a phenomenon called "target fixation." This tendency would increase progressively with increased distance between the subject and object until it eventually became exponential (i.e., too far away).

A unit for defining the size of a font. It's not a distance; this unit's measurement is only relative to the typeface's design.

An abbreviation for Portable Document Format. The PDF format was originally developed to share documents between different operating systems in the late 1980s. Any text document, image or page layout can be saved as a PDF file that includes all of the font information needed to display it without losing quality.

One or more words (typically at the end of a paragraph) that are separated from the rest of the text. Orphans are generally thought of as bad design, but it’s a matter of taste.

Text that is used to fill in a gap in a document.

The distance from the baseline to the top of a capital letter, number, or other upper-case glyphs.

The meeting point where two lines cross.

The way that a user navigates through a website, app, etc.

When you need to break a line of text and start on a new line in a text box.