about
'bout
/baʊt/Elision
In real speech
What happens to the sounds
The unstressed first syllable a- disappears: about → “bout”.
When to use it
How 'bout you? What 'bout tomorrow? Casual speech; in writing use about.
Casual → formal
Slang
'bout
Neutral
about
Formal
regarding / concerning
Sound notes
Elision: a sound disappears completely (often t, v, h or th).