This talk will introduce the concepts of Author Identification, Author Obfuscation, and Author Profiling. The main focus is on Author Profiling, namely cross-genre Author Profiling of textual data gathered from social media. Tweets, blogs, and reviews you leave online can reveal your age, gender, personality traits and a lot more about you. Author Profiling is used to create a socio-demographic profile of an anonymous person by analyzing the texts they write using Natural Language Processing and Machine Learning. It is used in forensic suspect profiling, customer-base analysis, and targeted advertising. This talk will give you an overview of this research field from a perspective of a computational linguist.