'Bootstrap' is a widely-used, open-source framework designed for front-end web development. It offers HTML and CSS-based templates for creating various interface elements like typography, forms, buttons, and navigation, along with optional JavaScript add-ons.

Created by Twitter's Mark Otto and Jacob Thornton in 2011, Bootstrap originated as a means to ensure consistency in internal tools. It quickly gained popularity for its responsive design features, simplifying the development of websites that are visually appealing across all devices, from desktops to mobile phones.

Bootstrap is renowned for its grid layout system, providing a versatile foundation for web page structuring. It also encompasses a range of pre-designed components and powerful jQuery-based plugins. The framework's customizability enables developers to craft specific aesthetics while maintaining streamlined and coherent code.

Throughout its development, Bootstrap has continued to evolve, introducing features such as Sass integration and enhanced responsive components. Its user-friendliness and comprehensive documentation have made it a go-to choice for developers, whether for quick prototyping or crafting full-fledged web applications.

In conclusion, Bootstrap is acclaimed for its user-friendly nature, adaptability, and customizable features. It serves as an invaluable resource for developers, facilitating the efficient creation of modern, responsive web pages and applications.