Japanese expression carrying the following English meanings: "excuse me", "pardon me", "I'm sorry", "thank you". Sumimasen is most often used as "pardon me", but it carries an apologetic/humble note. In combination with the hesitation noise "anoo...", it is the best way for foreigners to get the attention of Japanese strangers, teachers, doctors, hosts, etc etc. Don't use it for shopping/clerk scenarios, as the clerks themselves are supposed to take the humble attitude and the customer is given the utmost in courtesy -- he has no need of apologizing.

Omatase shite, hontoo ni sumimasen deshita.
I'm really very sorry for making you wait.

Anoo...sumimasen. Byooin wa doko desu ka.
Err, excuse me. Where is the hospital?

Compare with gomen nasai, a more formal apology for having done something wrong, and shitsuree shimasu, a more formal way of excusing oneself in the presence of superiors.

Written (sumimasen), no kanji.