SEMMA is an acronym introduced by SAS which stands for:

Sample, Explore, Modify, Model and Assess.

I had recently posted about the Data Mining & Knowledge Discovery Process which had following sequential steps:

Raw Data => cleaning => sampling => Modeling => Testing

SEMMA follows the similar sequential steps as we had seen in the data mining process. So while Data Mining process is applicable to any data mining tool out their, SEMMA helps when you use SAS enterprise miner. In fact, it has helped me quickly find the data mining functions available in SAS tool: