Grid

A CSS grid is defined using the grid value of the display property; you can define columns and rows on your grid using the grid-template-rows and grid-template-columns properties.

The grid that you define using these properties is described as an explicit grid.

If you place content outside of this explicit grid, or if you are relying on auto-placement and the grid algorithm needs to create additional row or column tracks to hold grid cells, then extra tracks will be created in the implicit grid. The implicit grid is the grid created automatically due to content being added outside of the tracks defined.