The text discusses the process of setting up preview deployments for a React application using Vercel and CircleCI, which facilitates the review and testing of code changes before merging them into the main branch. Preview deployments generate a live URL for each pull request, allowing stakeholders to view and test features in isolation, thereby enhancing the code review process. The guide details the steps involved, such as linking a GitHub repository to Vercel, configuring CircleCI to monitor and deploy pull requests, and ensuring secure access using environment variables. This workflow aims to streamline collaboration, improve feedback speed, and ensure secure and efficient code reviews by providing a live testing environment for each branch.