I'm a upcoming developer
Welocme back hero!!
So, Why we use group selector basically, The group selector is used to minimise the code. Commas "," are used to separate each selector in a grouping. This reduces the number of lines of code. The code also looks clean.
So, As you see that in this page here i applied Group Selector (e.g., h1, p, .classname) properties which are applicable for which are we selected or targets in CSS Page.
Note: In the style block, the group selector (e.g., h1, p, .classname), will target any element,tag,class,id etc. in CSS.