Pseudo classes and pseudo elements

Similarities: pseudo classes and pseudo elements are predefined and independent of document elements. They do not obtain element features based on IDs, classes, or attributes, but on elements in special states (pseudo classes ), or special content in the element (pseudo element ). Of course, the expression of pseudo classes and pseudo elements also uses ":" (colon) to distinguish it from other selectors.

Difference: the fundamental difference between pseudo-classes and pseudo-elements is whether they create new elements (abstraction ). From the perspective of imitating its meaning, if a new element needs to be added for identification, it is a pseudo element. Otherwise, if you only need to add a category to an existing element, it is a pseudo class.

Pseudo classes and pseudo elements