# Create a theme



A _layer_ is a set of features of a single kind, e.g. 'bookcases'.
A _layout_ is a set of layers, e.g. 'bookcases' + 'nature reserves'. They are shown together with some text on the left. They can be switched with the query parameter 'layout' in the url (thus by going to 'index.html?layout=bookcases')

If you want to make your own version of MapComplete, you create your own layout

- Clone the repo
- Build it
- Go into 'Customazations/Layouts' and copy a file there (e.g. bookcases)
- Change the text and layer selection
- Create you layers