Reports serve two main functions: to inform or to analyze. Informational reports simply present facts without analysis, while analytical reports provide data, analysis, and conclusions or recommendations. Reports can take different formats depending on their length, audience, and purpose - for example, short informal reports within an organization may use a memo format, while longer formal reports for external audiences use a manuscript format. The writing process involves analyzing the problem and audience, planning research, organizing findings, drafting the report, and revising. Style ranges from informal to formal depending on the context and purpose of the report.