There are generally considered to be two main types of household altar in Japan. One is the kamidana, a Shinto altar that enables communion with kami. The other is the butsudan, a Buddhist altar that is used to honour the Buddha as well as deceased relatives. Out of the two, the butsudan would seem to be the most common in Japanese homes.
There is a third type of feature that can be found in Japanese homes, tea houses, traditional inns and restaurants that could also be considered a kind of altar. [Read more]