grid-template attribute is the combined shorthand for grid-template-columns, grid-template-rows and grid-template-areas

grid attributes are combined shorthand forms of the six attributes of, 

1. grid-template-rows
2. grid-template-columns
3. grid-template-areas
4. grid-auto-rows
5. grid-auto-columns
6. grid-auto-flow

From the perspective of easy reading and writing, it is recommended not to merge attributes, so these two attributes will not be introduced in detail here.