Privacy means different things to different people in different contexts. Practically speaking, privacy is most noticeable when someone feels theirs could be or has been breached in some way.
Privacy can take different forms, for example: Bob shouldn’t acquire information about Alice; Bob shouldn’t interfere with Alice’s actions; Bob shouldn’t intrude into Alice’s space; Bob should tolerate Alice’s beliefs; Bob shouldn’t appropriate, use, or exchange Alice’s property.
Helen Nissenbaum argues that:
in any given situation, a complaint that privacy has been violated is sound in the event that one or the other types of the informational norms has been transgressed.
Norms vary, and privacy is therefore a social construct. Rather than talking in terms of a “right to privacy” then, it is more useful to reference the importance of ascertaining what privacy means in a given context and designing to respect it.