Norooz or Iranian new year is the beginning of the Spring. We calculate the exact astronomical start of the Spring and take that as the beginning of the year,. this exact second is called "Saal Tahvil".
Iranians consider Norooz as their biggest celebration of the year, before the new year, they start cleaning their houses (Khaane Tekaani), they buy new clothes, and they grow green grass(Sabze). For the actual Saal Tahvil, they put seven items on the table-linen that all start with "S". This is called "Haft Seen". These seven things are: Seeb(apple), Sabze(green grass), Serke(vinager), Samanoo(a meal made out of wheat), Senjed(a special kind of berry), Sekke(coin), and Seer(garlic). Sometimes instead of Serke they put Somagh(sumak, an Iranian spice).
After the Saal Tahvil, people hug and kiss each other and wish each other a happy new year. Then they give presents to each other, usually older ones to the younger ones. During the holidays, people go to see their relatives. Foods and snacks are usually prepared, snacks are "aajil"(a combination of defferent nuts with reisins and other sweet stuff) and fruits. When the guest is leaving, the host gives some "Eidi" to the kids, this Eidi is often some money; it is not very common to give toys as the Eidi.
At the thrteenth day of the new year, the people go to picnics. This is called Sizdah Bedar. This is the most popular day of the holidays among children because they get to play a lot! Also in this day, people throw the Sabze away, they believe Sabze should not stay in the house after "Sizdah Bedar".
Another tradition of the new year celebrations is "Chahar Shanbe Soori". It takes place before Saal Tahvil, at the last wednesday of the old year, well actually Tuesday night! People make fire and they jump from the fire and sing a little song :
Zardi-e Man az to
Sorkhi-e to az Man
It means: I will give you my yellow colour (sign of sickness), and you give me your red colour (sign of healthiness). This is becuse in the older times when Iraninas where Zoroasterin, they believed fire can cure people and take the sickness away.
Norooz is a fun time for all of the Iranians, old and young.
Have a happy new year. Norooz Mobarak.