Linked Selection

A mesh can be made of different linked parts that are not connected by edges and you may want to select one of them without selecting the others. There are two quick ways to select those linked parts:

Select one of the mesh’s vertices, edges, or faces, and press Ctrl + L. All the linked parts of the mesh will be selected.

With nothing selected, place the cursor on top of a mesh and press L to select the linked parts of the mesh. Press Shift + L to add and subtract from the selection.