Weka is a open source machine learning toolkit written in Java. It contains many machine learning algorithms like artificial neural networks, treelearners and support vector machines (SVM). Weka can be used as a stand alone application, using either the command line or the graphical user interface. Weka can also be used as a Java software library, so Weka's algorithms and supportive classes and objects can be used in any Java code.
Weka has been a popular machine learning toolkit for several years. This results in good community support. Weka is well documented. A book can be bought, or downloaded, which helps people new to Weka getting started using the toolkit's many features. Because Weka can be both used through a GUI and as a software library that can be included into your own code. Using the GUI, datasets can be explored and machine learning methods can be tried out before any code has to be written. The same implementations of those algorithms can then be used in your application's code.