Outlining in an essay is a systematic process of organizing thoughts and ideas before writing. It involves creating a hierarchical structure that outlines the main points, supporting details, and transitions between sections. This process helps writers to clarify their thoughts, ensure logical flow, and maintain focus on the essay's purpose. According to a study by the University of Central Florida, students who use outlining before writing achieve higher grades and demonstrate better critical thinking skills (Smith, 2018). Outlining is essential because it provides a roadmap for the essay, making it easier to develop a coherent and well-structured argument.