Some shadow effects may render text invisible in UAs that only support CSS1. This value indicates inter-character space in addition to the default space between characters. Values may be negative, but there may be implementation-specific limits. This value tells the user agent to adjust the spacing between characters so that the entire text of an element fits on one line. See also the 'font-size' property for related 'auto' behavior.
Character spacing algorithms are user agent-dependent.
This value indicates inter-word space in addition to the default space between words. Values may be negative, but there may be implementation-specific limits. Word spacing algorithms are user agent-dependent. In this example, the word-spacing between each word in H1 elements is increased by '1em'. Puts all characters of each word in lowercase.