The following items are thus *not* welcome:
- Do not add events such as a festival
- Do not add measurements of e.g. air quality, traffic counts, ... [Sensor.Community](https://sensor.community/) is the right place for this
- Do not add points that are only interesting to you (e.g. the route of your next trip). [UMap](https://umap.openstreetmap.fr) is the right tool for this
- Do not add privacy-sensitive information, e.g. the names of persons living in a house
- Do not add data about now demolished items, such as 'there was a battle here 100 years ago' or 'there was a school here, before it was completely demolished and rebuild'. This can be added to [OpenHistoricalMap](https://www.openhistoricalmap.org/) instead.
# How can OpenStreetMap data be reused?
OpenStreetMap data can be reused freely, including for commercial purposes. However, you have to:
1. Give attribution
2. Keep the data open - changes to data based on OpenStreetMap must be published under the same license.
See the [full copyright notice](https://osm.org/copyright) for details
This also means that we are *not* allowed to copy data from other maps. Do not enter data based on Google Maps!
# How does OpenStreetMap organise the data?
In OpenStreetMap, the geodata can be one of three types:
- **Points** which have a geocoordinate
- **Lines** which are a _list_ of points. Closed lines are used to represent polygons
- **Relations** which are a _list_ of points, lines and/or other relations.
All of those objects have a set of **attributes**. These are pairs of a **key** and a **value** which tell us what a point or line does represent. For example, `amenity=bench` represents a sitting bench.
You can find the meaning of all those keys and values on the [OpenStreetMap-wiki](https://wiki.openstreetmap.org/)
# OpenStreetMap does **not** have layers
Many traditional GIS-applications organise the data into layers.
OpenStreetMap does not do this. Consider this place:
This place has three functions:
- It is a shop, selling boardgames
- It is a café, where one can drink a tea (while testing one of the board games)
- It is a social inclusion project for people with a mental disability
In a traditional system with layers, one would either have to choose the most fitting layer (e.g. the layer `pub`, `shops` or `social facility`? ) losing the multi-facetted aspect of the place.
Another approach could be to add it to all three layers, duplicating the data. However, this makes maintaining the data harder.
Data can also be loaded and visualised from external sources. No changes can be made to this externally loaded data in that case.
# MapComplete _does_ have layers
A layer in mapcomplete describes a single type of object, e.g. _shops_, _toilets_, _benches_, _public bookcases_.
A layer tells us:
- What features to load from OpenStreetMap - thus what attributes the displayed data should have
- (Or where to find the data if we are using an external datasource)
- How these should be displayed on the map
- What should be shown in the popup...
- ... and what questions should be asked
- How to create a _new point_ onto the map
# MapComplete does have themes
A _theme_ is a **collection of layers**, with a title and a description.
For example, [cyclofix](https://mapcomplete.org/cyclofix) has many bicycle-related layers (of which items are shown on the map) and an introduction.
