--- layout: api title: "v2.1.0 JavaScript Library: L.IProjection" categories: api version: v2.1.0 permalink: /api/v2.1.0/l-iprojection ---

## IProjection

An object with methods for projecting geographical coordinates of the world onto a flat surface (and back). See Map projection.

### Methods

Method | Returns | Description
--- | --- | ---
`project( <LatLng> latlng )` | `Point` | Projects geographical coordinates into a 2D point.
`unproject( <Point> point )` | `LatLng` | The inverse of `project`. Projects a 2D point into geographical location.

### Defined Projections

Leaflet comes with a set of already defined projections out of the box:

Projection | Description
--- | ---
`L.Projection.SphericalMercator` | Spherical Mercator projection — the most common projection for online maps, used by almost all free and commercial tile providers. Assumes that Earth is a sphere. Used by the `EPSG:3857` CRS.
`L.Projection.Mercator` | Elliptical Mercator projection — more complex than Spherical Mercator. Takes into account that Earth is a geoid, not a perfect sphere. Used by the `EPSG:3395` CRS.
`L.Projection.LonLat` | Equirectangular, or Plate Carree projection — the most simple projection, mostly used by GIS enthusiasts. Directly maps `x` as longitude, and `y` as latitude. Also suitable for flat worlds, e.g. game maps. Used by the `EPSG:3395` and `Simple` CRS.