Typography: double f

[DaveC426913]

Just noticed this is an online article.

Is 'ff' a ... ligature? Or a type face style?
Or is it a display style?

Where in the authoring, publishing, display process might this occur?

 

[Hill]

See https://en.wiktionary.org/wiki/ff.
I still don't know how to do it on a keyboard, though.

 

[BillTre]

Its a ligature. A combination of two adjacent letters. They can be enabled in certain publishing (layout) software (like Affinity or In Design). When the two letters are adjacent they can be combined into a single ligature (as a software option).
They can happen in different typefaces (perhaps depending on the typefaces being able to make the ligature). I would guess not all typefaces can do this.
Its a kind of old style typesetting, like using a Big letter (a drop cap) to start off a paragraph.