The Merge tool will take data from two or more layers, or tables, and combine them into a new single output. This is useful if you get the same type of data from multiple sources or locations. For example, let's say you are working with a regional emergency response group and you are trying to develop a regional evacuation plan. You receive road data from multiple jurisdictions. You can use the Merge tool to combine them all into a single layer.
The Merge tool can be found in the Data Management Tools toolbox and General toolset. The Merge tool can be used to combine points, lines, polygons, and even standalone tables. You can only merge similar features, meaning you can only merge points with points, lines with lines, and polygons with polygons.
Here is another example of when you might want to use the Merge tool. You are responsible for inventorying all the fire hydrants within the city. So, you go out over the course of several days collecting...