These programs, like other language parsers, form the basis of Natural Language Understanding (NLU) systems. Parsers are what allow applications like Google Now and Siri to understand the words you are either speaking or typing, label each word by its syntax and then discern your intent from what you've said/typed. The problem is, sentences become more complex and harder to decipher the longer they are. A sentence comprised of just 20 words may have hundreds of different syntax interpretations. Luckily, Parsey McParseyface is ranked as the most accurate parsing model currently available with a comprehension accuracy of about 95 percent.