* "Como está?" (formal, singular) - This is the most common way to ask "How are you?" to someone you don't know well or are showing respect to.
* "Como estás?" (informal, singular) - This is used with friends, family, or people you're close to.
If you're talking about the state of something, you would use "Como está" (formal) or "Como está" (informal) followed by the noun.
For example:
* "Como está o tempo?" (How is the weather?)
* "Como está o seu dia?" (How is your day?)