Rosh Hashanah is a special festival which celebrates Jewish New Year. It literally means 'head of the year'.
The festival lasts for two days and this year it starts on 9 September.
This is because the dates of Jewish festivals come from the Hebrew Calendar, so the Jewish New Year begins in autumn, as opposed to on 1 January.
Find out more about what it means and how it is celebrated below.
Rosh Hashanah is a celebration of the creation of the world and marks making a fresh start.
It is a time for people to reflect on the past year and to ask for forgiveness for anything wrong they feel they have done.
They can also think about their priorities in life and what it important to them.
The festival also marks a time of judgment, when Jewish people believe that God balances a person's good acts over the last year with their bad acts, and decides what the coming 12 months will be like for them.
During Rosh Hashanah, Jewish people will traditionally greet each other with L'shanah tovah, which means "for a good New Year".
Many Jewish families will spend some of Rosh Hashanah at a Synagogue. This is the name given to the building where Jewish people go to worship.
One of the traditions of Rosh Hashanah is to blow a big horn called a Shofar. One hundred notes are blown on the horn to create a special rhythm.
The Shofar is one of the world's oldest known wind instruments.
The sound of the Shofar marks the beginning of the ten-day period called the 'Days of Awe', which lead up to another Jewish festival called Yom Kippur.
Yom Kippur is the most solemn day in the Jewish calendar. It means Day of Atonement and people don't eat or drink for 25 hours. It's a day to reflect on the past year and ask God's forgiveness for any sins.
During Rosh Hashanah, food is also really important.
Slices of apple are dipped in honey to symbolise a sweet new year ahead. Honey cake is eaten too.
Some Jewish people make a sweet carrot stew called tzimmes, and bread called Challah (or Hallah) is baked into a round shape to symbolise the circle of life and the end of the year. This is different to the plaited bread Challah loaf which Jewish people typically eat on the Sabbath.
You might also find a pomegranate on the table because there is a tradition that they contain 613 seeds. These represent one for each of the commandments a Jewish person is supposed to keep.