Example
Before
That's a great idea
After
tHaT's A gReAt IdEa
How letters are counted
Only letters count toward the pattern. Spaces, numbers, and punctuation are skipped, so the alternation carries on smoothly from one word to the next.
Where people use it
Alternating case is used almost entirely for sarcasm and jokes in chats and social posts. Some screen readers handle it poorly, so avoid it anywhere accessibility matters.