CSS selectors, these are used to select a particular or group of tags sharing some common thing like class name, id, (siblings), tag name.
Selectors follow specificity (say priority), for example if there is a tag having class =
a and id =
b. If you're selecting a element with
b then CSS property given to
b are applied.
You can read more about css selectors here.
selects all the elements, denoted by
This selector selects all elements with same tag name.
This selector selects all elements with class name that is selected.
This selector selects element with a id.
many elements can have one id, but use class for this, it's just convention.