What selectors are there in css?

First let’s take a look at what selectors are there? ? ?
1. Basic selector:
html tag selector: select elements through html tags.
①All html tags can be used as selectors.
②No matter how deep the tag is hidden, it will be selected.
③ Select all tags instead of a specific tag.
So what we set through the html tag selector are some common issues.
id selector:
① Any tag can have an id attribute and attribute value (because id is a global attribute). The ID name cannot be named arbitrarily.
It is case sensitive. The ID name can have numbers, letters, and underscores, but it must start with a letter.
Camel case nomenclature: small camel case nomenclature, big hump case nomenclature.
For example: testStudent (small hump) TestStudent (big hump)
②The naming of id cannot be repeated.
class selector:
① Any tag can use the class attribute (the class attribute is also a global attribute).
②The class attribute name can be repeated.
③A class attribute can have multiple class attribute values.

2: Comprehensive selector
1. Descendant selector (div p)
2. Intersection selector (div.p)
3. Union selector (div, p)
4 Child element selector (div>p)
5 Sequence selector (ul li:first-child; ul li:last-child)
6 Adjacent sibling selector (div+p)
7 Ordinary brother selector (div~p)

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