How do I make a web map?

A good web map starts with a well designed idea that can be mapped. Before choosing the technology to create a web map, or even before gathering data for the map, it is important to determine the web map's purpose. It helps to ask,

"What story do I want this web map to tell?"
"Who is the intended audience for my web map?"

Once the purpose and audience for the web map are determined the next step is to choose which technology to use to create the map.

Map Making Tools

There are variety of mapping tools available on the web that cater to various skill levels. Some tools are free and others require payment; some tools are easy to pickup and use while others are more complex and require a steep learning curve. This is a list of various tools you can use to create a web map.

Tools for Novice Users

Here is a list of map making tools that are designed for use by novice web users. These tools require little to no web programming knowledge to create web maps.

Tools for Experienced Users

This list of tools are for the more experienced web user. These tools have a high learning curve and require basic knowledge about programming on the web. Despite the higher learning cure these tools can provide greater control and flexibility when creating web maps.

Google Maps API
Google Earth
ArcGIS Explorer
Leaflet
Polymaps
QGIS
TileMill: MapBox's web map design toolkit that runs on your local computer. Use this to create web maps you can upload to an account on MapBox.com.
ArcGIS for Desktop

Finding Data

Finding data is essential to constructing a good web map. What data to gather for the web map is based on the purpose of the map. Geospatial data used in a map can be classified as either raster or vector. Raster data is characterized as a two-dimensional grid of cells. Each cell may contain a discrete, continuous, or null value. These values represent attributes of measurable things on earth like land use or temperature. Color values can be assigned to each value in the grid to help visualize the raster data in a map. Vector data uses primitive geometrical components to represent geographical features on the earth. These geometries are points, lines, and polygons. Points are used to represent a feature that can be best depicted as a single point of reference on a map. At small scales on a map of a country in the world cities could be represented using points. Lines can represent linear features like roads, railways, rivers, and trails. Lines can also be used to depict contour lines which are often used to show elevation using topographic lines. Polygons are used to depict features that cover an area on the surface of the earth. Waterbodies, geopolitical boundaries, land parcels, parks, and land use areas can all be represented using a polygon geometry. Choosing the format of geospatial data to use depends upon the purpose and audience of the web map. The following links are not intended to be a comprehensive list of data sources but may provide a useful starting point when creating a web map.

Tutorials

Below are some tutorials to help walkthrough the steps of creating a web map.