--- title: Values introduction: > Sass supports a number of value types, most of which come straight from CSS. Every [expression](syntax/structure#expressions) produces a value, [variables](variables) hold values. Most value types come straight from CSS: --- * [Numbers](values/numbers), which may or may not have units, like `12` or `100px`. * [Strings](values/strings), which may or may not have quotes, like `"Helvetica Neue"` or `bold`. * [Colors](values/colors), which can be referred to by their hex representation or by name, like `#c6538c` or `blue`, or returned from functions, like `rgb(107, 113, 127)` or `hsl(210, 100%, 20%)`. * [Lists of values](values/lists), which may be separated by spaces or commas and which may be enclosed in square brackets or no brackets at all, like `1.5em 1em 0 2em`, `Helvetica, Arial, sans-serif`, or `[col1-start]`. A few more are specific to Sass: * The [boolean](values/booleans) values `true` and `false`. * The singleton [`null`](values/null) value. * [Maps](values/maps) that associate values with keys, like `("background": red, "foreground": pink)`. * [Function references](values/functions) returned by [`get-function()`][] and called with [`call()`][]. [`get-function()`]: functions/meta#get-function [`call()`]: functions/meta#call