Detailed Explanation of Bootstrap 5 Grid System: Containers, Rows, Columns, and Breakpoint Settings

The Bootstrap 5 grid system is based on a 12-column layout concept, enabling rapid implementation of responsive web layouts. Its core is a three-level structure of "Container - Row - Column": The container acts as the layout boundary, with two types: the fixed-width centered `.container` and the full-screen `.container-fluid`. Rows wrap columns, counteract container padding, and utilize flex for automatic line breaking, with rows must be nested within containers. Columns are the content units, whose widths are controlled by the `.col-[breakpoint]-[number]` class (1-12 columns). Breakpoints include `sm` (≥576px), `md` (≥768px), etc., with columns defaulting to 12 columns or automatically adjusting based on breakpoints. Column spacing can be modified via the `.gap-*` class, and content alignment supports control in text (text-*) and vertical (align-items-*) directions. Media queries are unnecessary; class name combinations can adapt to devices such as mobile phones, tablets, and computers.