Weka is a collection of machine learning algorithms for data mining tasks. The algorithms can either be applied directly to a dataset or called from your own Java code. Weka contains tools for data pre-processing, classification, regression, clustering, association rules, and visualization. It is also well-suited for developing new machine learning schemes.
Weka is open source software issued under the GNU General Public License.
We have put together several free online courses that teach machine learning and data mining using WEKA. Check out the website for the courses for video lectures and details on how to enrol.
Yes, it is possible to apply Weka to big data!