Those properties define the number of columns and rows in the grid, and they also set the width of each column/row.

The following snippet defines a grid with 4 columns each 200px wide, and 2 rows with a 300px height each.

.container {
  display: grid;
  grid-template-columns: 200px 200px 200px 200px;
  grid-template-rows: 300px 300px;
}

Here’s another example of a grid with 2 columns and 2 rows:

.container {
  display: grid;
  grid-template-columns: 200px 200px;
  grid-template-rows: 100px 100px;
}

Lessons in this unit:

0:	Introduction
1:	▶︎ grid-template-columns and grid-template-rows
2:	Setting columns and rows dimensions
3:	Gap between the cells
4:	Span items on multiple columns and/or rows
5:	Minimum row width
6:	Layout using grid-template-areas
7:	Example: simple grid layout
8:	Example: grid layout with header, sidebar, content and footer