[1]. Betweenness centrality is an indicator of a node's centrality in a network. It is equal to the number of shortest paths from all vertices to all others that pass through that node. A node with high betweenness centrality has a large influence on the transfer of items through the network, under the assumption that item transfer follows the shortest paths.
[2]. To visualize the concept, you take all the shortest path from all nodes to all nodes on your graph. In each path, if one node is traveled, you add him « one point ». When all the paths are done, you have a ranking where some nodes are traveled a lot and some a few (almost never). This describes the Betweenness centrality - if a node have a high number, it has a high betweenness centrality.
How to check betweenness in Gephi?
1. Import your network data.
2. Calculate Network Diameter with [Run]
3. Rank the Nodes by selecting "Betweenness Centrality" after step 2.
3. You could also apply Filter to see limited network [Attributes] -> [Range] -> [Betweenness Centrality]
Reference:
[1]. http://en.wikipedia.org/wiki/Betweenness_centrality
[2]. http://matthieu-totet.fr/Koumin/2013/12/16/understand-degree-weighted-degree-betweeness-centrality/