Bit is a tool that enables the creation of reusable CSS components, allowing developers to encapsulate styling rules into independent modules that can be shared across various projects and frameworks like React, Angular, and Vue. By using Bit, developers can maintain a consistent design system and UI library through modular components that can be incrementally updated without disrupting existing project structures. The tool supports a range of styling solutions, exemplified by SCSS components for defining color schemes, spacing, and breakpoints, which are used to build complex structures like a container component with background color and media queries. Bit's intelligent dependency management and automatic tagging ensure that changes to any component propagate through dependent components, keeping them in sync across different projects and frameworks. This capability reduces manual overhead, fosters code reuse, and maintains consistency, offering teams the ability to work autonomously while ensuring that their codebases remain current and manageable.