Chaharshanbah Suri is an Iranian festival celebrated by all Iranians. Azerbaijani Turkish and Kurdish people also celebrate except Iranians. The word Chaharshanbah mean Wednesday and the word Suri mean light in Persian language. On the eve of last Wednesday of the Persian new year -Nowroz- , people spend that night with a fire. The celebration starts in the evening with making bonfires in the streets. People jumps over those bonfires, while jumping they are also singing a song which is special for that night.
Another popular custom is to bang spoons and plates together. Women disguise themselves in chadors with a spoon and a plate, go from door to door -to neighbors' houses- , banging a spoon against a plate and asking for treat or money. The neighbor puts a small gift as fruits, nuts or a trinket etc., frequently never puts money.
Another custom is Iranians and Azeri people believe that that night good for divination. Iranians call it Fal-goosh. Someone makes a wish and stands at the corner or behind the door of a room, and listening to the conversation. According to conversation, that person know his fortune. If that person can't understand anything about conversation than ask someone who can interpret (as grandmother or mother).
Briefly, all Iranians love Chaharshanbah Suri! :)