This e-portfolio project provides a comprehensive overview of e-commerce development, encompassing various crucial aspects of establishing and managing an online business. The project begins with the foundational steps of building e-commerce applications, mobile sites, and websites, emphasizing the importance of defining a mission statement, identifying the target audience, and developing a strategic plan, including budgeting and SWOT analysis. It then delves into the System Development Life Cycle (SDLC) and various models like rapid application, spiral, and waterfall, highlighting the importance of design, testing, and optimization for revenue generation. The project continues with an examination of payment and security systems, addressing common threats like malware, phishing, and denial-of-service attacks, and explores the use of encryption, digital signatures, and firewalls to protect e-commerce businesses. Furthermore, the e-portfolio covers e-commerce business models, detailing key components such as revenue models, value propositions, competitive environments, and market opportunities, and explores different business models like B2C and B2B. The project concludes by examining advertising and marketing concepts, including consumer behavior, decision-making processes, and various online marketing strategies like lead generation, email marketing, and mobile marketing, along with pricing and customer retention strategies. The project provides a holistic view of building a successful e-commerce business.