Buffer units in Geographic Information Systems

Question

Why the unit of buffer is in meter? Or by default they are found as meters?

Answer 1

As commented by atxgis: "Buffer is generally in map units, which is defined by your coordinate system."

While you can select a specific unit when buffering in software such as ArcGIS, the default in most GIS applications should be the units from your coordinate reference system. For example, when working in a US State Plane projection - which has foot as the unit - would default to foot in the buffer processing tool. If you look up the reference system of your data, you can view the units.