The master's thesis explores the concept of e-commerce and its evolution in the world of online business and software development. It focuses on analyzing the design of user experience and interfaces in e-commerce, as well as investigates aspects of accessibility and web design elements. E-commerce, or electronic commerce, represents an online business model in which products and services are sold over the Internet. This phenomenon has become highly significant in modern business due to its global availability, convenience for consumers, and the ability to expand markets without geographical limitations. In today's digital environment, web stores are increasingly oriented towards providing an exceptional user experience. With the growing number of customers, diverse customer expectations arise, prompting web stores to adapt their user interfaces to meet various needs. This work aims to elucidate in detail the elements of user interface design in web stores and how each of these elements affects the overall user experience during online shopping. Furthermore, a comprehensive analysis of two web stores, ASOS and About You, was conducted, comparing their design and functionality in accordance with the main components of e-commerce, including the homepage, navigation, search, product pages, and the checkout process.