Recordings were made on the OpenBCI Cyton board which records the micro voltage from electrodes placed on the scalp. These voltage changes can be used to classify different mental states with the help of machine learning. I studied filtering via signal processing, artifact removal via independent component analysis, and target non-target difference via P300 response. Using these methods, I was able to build a P300 speller which would allow a person to spell words and make sentences by mentally acknowledging when the letter they want is highlighted on screen.