The ID Selectors
You can define style rules based on the id attribute of the elements. The ID Selectors denoted by # keyword
You can apply a style to many selectors by separate selectors with a comma.
h1, h2, h3
*These properties will be applicable to h1, h2 and h3 element.
The Attribute Selectors
You can also apply styles to HTML elements with particular attributes.
The advantage to this method is that the these properties will applied only to the text boxes and not to button or radio button. (Because if we will create a rule of input only then it will cover all elements starts with input tag).
The Child Selectors
The Child Selectors are very similar to descendants but have different functionality.
body > p
This rule will render the entire paragraphs font in 18px if they are a direct child of the <body> element. Other paragraphs would not have any effect of this rule.
The Universal Selectors
The Universal Selectors are used to cover all elements within a document so the same is also called as page properties
The above property will apply on the content of every element in our document