# CSS Selectors

CSS selectors define the elements to which a set of CSS rules apply.


## ID selector

Selects an element based on the value of its id attribute. There should be only one element with a given ID in a document.


```
#id-selector {
  /*   */
}
``` 

## **Class selector**
Selects all elements that have the given class attribute. Syntax: .classname Example: .index will match any element that has a class of "index".


```
.class-selector {
/*        */
}
``` 

## Tag selector
Selects all elements that have the given node name. Syntax: elementname Example: input will match any <input> element.


```
body {
/*        */
}
``` 

## **Attribute selector**
Selects all elements that have the given attribute.


```
a[href$=".org"] {
  color: red;
}
``` 

## **Universal selector**
Selects all elements. Optionally, it may be restricted to a specific namespace or to all namespaces.


```
* {
  color: green;
}
```