The Difference Between Explicit and Implicit Grids
Grid Layout finally gives us the ability to define grids in CSS and place items into grid cells. This on its own is great, but the fact that we don't have to specify each track and we don't have to place every item manually makes the new module even better. Grids are flexible enough to adapt to their items.
This is all handled by the so called explicit and implicit grid.
Read the full article on csstricks .