The Big Garden Birdwatch is the world's largest garden wildlife survey and everyone is invited to take part.

Organised by the RSPB, the event takes place over three days from Saturday, January 27 to Monday, January 29.

The study provides a snapshot of bird numbers across the UK and allows the RSPB to monitor trends and understand how birds are doing.

Joining in is simple, here's how you can get involved:

• Choose a good place to watch from

Think about which window gives the best view of your garden and make sure you have a comfy place to sit. If you don't have a garden, you can pop down to you local park or green space.

• Relax and watch the birds for one hour

• Remember to keep count

Count the maximum number of each species you see at any one time. For example if you see a group of three house sparros together and later another two, and after that another one, the number to submit is three. That way you are less likely to double-count the birds.

• Visit the Big Garden Birdwatch website

Head on over to rspb.org.uk and tell them what you've seen. You can also print out a paper form, which is free to post back to the RSPB.

But what if you don't see anything?

If you complete the hour and don't see a single bird, the RSPB would still like you to submit your findings. A total of 0 birds is still useful data as it's important to know where there were lots of birds and where there weren't.

What's the history of Big Garden Birdwatch?

In 1979 the RSPB were looking for a winter activity their junior membership could take part in. Realising that it would be cold and dark, they decided a garden activity would be best. So they asked members to count the birds in their gardens to work out what the UK's top 10 most common garden birds were.

Biddy Baxter, then editor of Blue Peter, liked the idea so much she included the survey on one of the programmes and thanks to the coverage more than 34,000 people took part.

In 2001 the activity was opened up to adults as well as children and has continued to grow into the regular event it is today.

• Will you be taking part in the Big Garden Birdwatch? Let us know in the comments below.