Leaflet, developed by Vladimir Agafonkin and a team of dedicated contributors, is a lightweight yet robust library for interactive maps and is designed with simplicity, performance and usability in mind. It is specifically aimed at being mobile-friendly. It has all the features most developers ever need for online maps. Leaflet can be extended with a very large number of plugins.
Leaflet has support for tile layers, markers, popups, polygons and more, as well as user interactions such as mouse scroll-wheel zoom on the desktop and multi-touch zoom for iOS, Android 4.0 and later, and Windows Phone 8. It can load feature data from GeoJSON files, style it and create interactive layers. This includes markers with popups when clicked. It supports Web Map Service layers, GeoJSON layers, Vector layers and Tile layers.
Leaflet code can create polygons and interactivity (including mobile touch screens and mouse clicks) on a map. It doesn’t have its own mapping data and a base map layer is needed. While a project tutorial suggests CloudMade since it initially created and open-sourced Leaflet it works with other mapping platforms too. These include MapBox and OpenStreetMap.
Leaflet is comparable to the proprietary, closed source Google Maps API and Bing Maps API.