Failing to speak can also be rude: a rude person might pointedly ignore a legitimate and polite greeting or question to communicate disregard for the other person, or might fail to express appropriate thanks for favors or gifts by way of communicating either a sense of selfish entitlement or a disregard for the efforts of the giver. Sometimes people will leave very short gaps when speaking that may allow another person to begin speaking on a subject, however that can vary, and sometimes two or more people speaking at the same time can be considered rude. Which acts and communications require a response from which persons, under which circumstances, and what kind of response is required, depends on the culture and the social situation of the people concerned.