I'm a German software developer who needs to add a parameter to a function that lets users choose if the created text "sticks" to the left, to the right, or is (horizontally) centered. For this concept I have found three expressions: (1) text justification (2) text alignment (3) quadding.
Is there any difference between the three choices in how they are used / what they mean?
Text alignment
From writing HTML, I know text alignment, e.g. mozilla docs.
It's also called "align" in Google Docs and Libre Office Writer:
Text justification
The same concept is called "text justification" in the PDF specification.
Quadding
I have only ever seen this in the PDF specification. There it is used as a synonym for "text justification".
The best explanation what this means comes from http://www.happydragonspress.co.uk/tips/beginners/justification.shtml :
Em spaces are sometimes grouped in with Quads. Quads (or Quadrats) are like extra wide spaces, in multiples of 1 Em: 2 Em, 3 Em, 4 Em and occasionally 5 Em. These extra wide spaces are particularly useful for centering things and, above all, for poetry.
So quads are a tool to implement centering.
Other occurences:
Google N-Gram
Looking at Google NGrams, text alignment seems to be by far the most common one:
Justification vs Alignment
According to https://yesimadesigner.com/justification-vs-alignment/ and https://www.shutterstock.com/blog/justify-vs-align-guide-to-type-alignment
- Uses "justified" as one type of text alignment. It's called "justified" in Google Docs / Writer as well.
- Maybe even more precise would be that text is either justified or aligned. If it is aligned, it can be left/center/right aligned.
Best Answer
These undoubtedly have proper meanings that typesetter would know about.
But 99% of English speakers are not typesetters, and we only get a vague idea from the use of these words in word processing applications, or perhaps from writing HTML and CSS.
Alignment is how the rows of text line up: Do they line up to the left, leaving the right part ragged, or to the right, leaving the left ragged. Or the alignment might be at the centre, leaving both left and right ragged.
I suppose you could align in other ways, for example making the first letter of the second word of each row of text line-up, or making a pattern (as in Lewis Carroll's "Mouse's tale")
Justification is about making both left and right edges line up straight, usually by inserting extra space between the words. And also people use "justification" to talk about not justifying the text but leaving it ragged - so justification comes to mean the same as alignment... and the real typesetters start to seethe at how muggles like me are using their words wrongly.
Quadding is a technical term that isn't used by non-specialists.
You are just talking about how the text lines up, so use "alignment". if it is user-facing text.