Text level mark-up

CSS (an abbreviation; abbr markup used)
radar (an acronym; acronym markup used)
bolded (b markup used - just bolding with unspecified semantics)
big thing (big markup used)
large size (font size=6 markup used)
Courier font (font face=Courier markup used)
red text (font color=red markup used)
Origin of Species (a book title; cite markup used)
a[i] = b[i] + c[i); (computer code; code markup used)
here we have some ~~deleted~~ text (del markup used)
an octet is an entity consisting of eight bits (dfn markup used for the term being defined)
this is very simple (em markup used for emphasizing a word)
Homo sapiens (should appear in italics; i markup used)
here we have some inserted text (ins markup used)
type yes when prompted for an answer (kbd markup used for text indicating keyboard input)
Hello! (q markup used for quotation)
He said: She said Hello! (a quotation inside a quotation)
you may get the message Core dumped at times (samp markup used for sample output)
this is not that important (small markup used)
overstruck (strike markup used; note: s is a nonstandard synonym for strike)
this is highlighted text (strong markup used)
In order to test how subscripts and superscripts (sub and sup markup) work inside running text, we need some dummy text around constructs like x₁ and H₂O (where subscripts occur). So here is some fill so that you will (hopefully) see whether and how badly the subscripts and superscripts mess up vertical spacing between lines. Now superscripts: M^lle, 1^st, and then some mathematical notations: e^x, sin² x, and some nested superscripts (exponents) too: e^x² and f(x)^{g(x)^a+b+c} (where 2 and a+b+c should appear as exponents of exponents).
text in monospace font (tt markup used)
underlined text (u markup used)
the command cat filename displays the file specified by the filename (var markup used to indicate a word as a variable).

Some of the elements tested above are typically displayed in a monospace font, often using the same presentation for all of them. This tests whether that is the case on your browser:

This is sample text inside code markup
This is sample text inside kbd markup
This is sample text inside samp markup
This is sample text inside tt markup