Data for machine learning applications can come from any number of sources; it may be emailed to you as a CSV file, it may come from pulling down server logs, or it may require building a custom web scraper. Data is also likely to exist in any number of formats. In most cases, you will be dealing with text-based data, but, as we'll see, machine learning applications may just as easily be built that utilize images or even video files. Regardless of the format, once you have secured the data, it is crucial that you understand what's in the data, as well as what isn't.