Extra Edges Tool
The 
Extra Edges tool works like the
Merge Faces tool but operates on edges. Instead of merging
two faces by selecting the faces, you select the edges between faces to remove the extra
edge and merge the faces.
You should only merge faces that are tangent or close to tangent. Otherwise, the results may not be what you expect.
Note: The Extra Edges tool is only intended to be used as preparation for analysis.
Merging faces simplifies the model by removing edges and makes the model more
difficult to modify.
This section contains the following topics: