The document discusses error analysis (EA), which is defined as the study of errors made by second language learners. EA aims to identify, describe, classify, quantify, and analyze errors to better understand the language acquisition process and provide insights for teaching. It views errors as natural parts of learning rather than signs of failure. The document also discusses the differences between errors and mistakes, and outlines some key steps and purposes of conducting EA, such as documenting errors, identifying their sources and causes, and using findings to improve instruction.