This report, designed as a training handbook for IT apprentices, comprehensively covers various aspects of computer systems. It begins by defining computer systems and explores different types, including personal computers, workstations, and supercomputers. The report then evaluates the role of computer systems in diverse office environments such as education, business, and healthcare. It identifies a range of computer systems commonly used in offices, including computers, software, and networking. The report further delves into hardware and software components, differentiating between open-source and closed-source software. It analyzes different operating systems and their suitability, describes characteristics of various user styles, and evaluates components to meet user needs within a professional environment. Finally, the report concludes with a section on configuring a computer system, providing a practical guide for apprentices. The content is structured to meet the learning outcomes of the OTHM Level 3 Foundation Diploma in Information Technology, providing a solid foundation in computer systems knowledge.