Absolute Measurement: Absolute measurements are measurements of fixed values. Points and picas, which are the basic typographic measurements, are all equally fixed values. The absolute measurements are expressed in restricted terms that can’t be altered.
Relative Measurement: Relative measurement is linked to type size. This defines the relationship between spacing and type size. An example would be Ems and ens. They are prime examples of relative measurements that have no prescribed, absolute size. The size is the size of type that is being set.
Points: Points are measurements that are used to measure the type size of a font. (Ex. 7 pt Times New Roman.) The measurement refers to the height of the type block, not that letter itself. Basic typographical measurement is an absolute measurement equivalent to 1/72 of an inch.
Picas: A unite of measurement that is equal to 12 points that is commonly used for measuring lines of type. There are six picas (72 points) in an inch which equals 25.4 millimeters.
x-height: x-height is the height of the main body of the lowercase letter. (height of lowercase letter).
The Em: The em is a relative unit of measurement used in typesetting to define basic spacing functions and is linked to the size of the type. IT is a relative measurement that is the type size increases, so does the size of the em. If it decreases, so does the em.
The en: The en is a unit of relative measurement that is equal to half of one em. In 72pt type, an en would be 36 points. An en rule is used to denote nested clauses, but it can also be used to mean “to” in phrases such as 10-11 and 1975-1981.
Dashes: Type uses various dashes, short horizontal rules that serve carious specific functions such as em rules, en rules, and hyphens.
Em Dash: An Em dash is used to form lines and house nested clauses. A standard joining em dash can cause spacing issues as it has no side-bearings and fills its bounding box so that it touches the surrounding characters. A row of em dashes would form a solid line. Punctuating em dashes are shorter and provide space for characters allowing them space. A row of punctuating em dashes forms a punctuated line.
En Dash: An en dash is half of an em rule and is used to separate page numbers, dates, and to replace the word “to” in constructions implying movement.
Hyphens: A hyphen is one third of an em rule and is used to link words. It serves as a compound modifier where two words become one, such as an x-height. It breaks syllables of words in text blocks like geo-graphy and serves to provide clarity such as re-serve rather than reserve.
Alignment: Alignment refers to the position of type within a text block, in both the vertical and horizontal planes.
Justification: Justification used three values for type settings: minimum, maximum, and optimum values.
Flush Left: A flush left if an alignment that follows handwriting, with text tight and aligned to the left margin and ending ragged on the right.
Flush Right: Right aligning text isn’t as common as others because it is harder to read. It is used for picture captions or other accompanying texts as it is clearly distinct from body copy.
Letter Spacing: Space between words making an open pathway for letterforms.
Kerning: Kerning is the removal of space between characters.. This and letterspacing can be done manually or automatically.
Tracking: Adjusting the tracking affects the amount of spacing between characters.
Word Spacing: Word Spacing adjusts the amount of space between words.
Widow: A single word at the end of a paragraph.
Orphan: An orphan is something that should be avoided. It is one or two lines of a paragraph that separate the main body to form a new column.
Leading: Leading is a hot metal. The term came from lead strips that were inserted between text measures in order to space evenly. Ex. Type was specified as 36 pt type with 4 pt leading. Now, leading refers to the space between the lines of text in a text block.
Indent: Indentation gives the reader an easy access point to a paragraph. The length of the indent can be related o the point size of the type such as a one em indent. The grid, such as a basic grid from a golden section, can determine the points.
First Line Indent: The text in a first line indent comes from the left margarine in the first line of the second and subsequent paragraphs. The first paragraph in a document following a heading, subhead, or crosshead is not normally indented, as this is an awkward space.
Hanging indent: A hanging indent is like a running indent except the first line of the text is not indented.
Source: Fundamentals of Typography
