Mitzvah Day is a day when Jewish people give their time to help others - this year it's on 17 November.
It's not just people from the Jewish faith who celebrate Mitzvah day, people from lots of different religions get involved too.
The day is dedicated to doing good things for other people in your community.
This year there's a green theme - so people are being encouraged to do something to help the environment.
How did Mitzvah Day start?
Mitzvah Day was started by a Jewish lady called Laura Marks in 2005.
Laura wanted to bring all the different faiths in the UK together for one day - to do something good for their communities.
Mitvah has three important values for anyone getting involved.
Tikkun Olam - which means healing - Mitzvah Day helps people understand that being kind to others and our planet is important.
Gemilut Chasadim - this means act of loving kindness - acts of kindness are a part of everyday Jewish teachings but Mitzvah Day encourages everyone to be kind.
Tzedek - this means honest and just - the Jewish faith teaches that you should do kind things to be loving not just because it feels good.
The word Mitzvah is a Hebrew word and in the Jewish faith it is taken to mean a good deed done out of religious duty.
This means that people who are Jewish do good things on this day because they believe it's what God would want them to do - to be kind and loving.
Lots of other people from lots of other religions - like Islam, Christianity and Buddhism, also get involved because they also think its a good thing to do.
People do things all year round for Mitzvah Day as well as coming together to help others on the day itself.
This year for Mitzvah there is a big focus on recycling and tree planting.
Some people have arranged litter picking in their local area or beach cleans, others have made bird feeders.
Some have volunteered at animal rescue charities or made bags from old newspapers.
It's all about doing something kind for someone else or the wider community.
What do you think?
Are you doing something for Mitzvah Day? What would you do to help someone else? Do you think it's a good idea?
Let us know in the comments below.