Branding
Tone of voice
Tone of voice is the defined way a brand speaks: vocabulary, sentence length, how it addresses people and what it avoids. It is the verbal counterpart to a visual identity and keeps communication consistent no matter who writes it.
What it means in practice
The most useful form is not a list of adjectives like friendly and professional, which everyone interprets differently. What works is a say this, not that table with real sentences from your own communication, plus a list of banned words.
A test we run with clients: take three competitor posts, remove the logos and have your team guess which one is yours. If nobody can tell, you do not have a tone of voice yet.