Menus, widgets, and blocks: which tool places what

Menus, widgets, and blocks: which tool places what

These three control different parts of your layout, and mixing them up causes a lot of confused clicking.

— Menus build your navigation links, the row of pages across the top. Edit them under Appearance, Menus.
— Widgets are small content units (search box, recent posts) that go in side areas and footers.
— Blocks are the pieces inside a single post or page.

A modern wrinkle: newer themes turn footers and sidebars into blocks too, so 'widgets' may now be edited with the block editor.

Quick guide: changing the top navigation, use Menus. Adding a footer search box, use widgets or blocks. Building the body of a page, use blocks.

In plain words: menus for navigation, widgets for sidebars and footers, blocks for the page itself.