WYSIWYG or WYSWYG stands for What you see (is) what you get (something like Microsoft word). Now, FCKEditor (a web base html editor) is trying to change the old style plain textarea box to something more interesting like Ms word.
FCKEditor come with a bunch of awesome feature, below is just part of the feature:-
# Multi browser compatibility
# Outputs XHTML 1.0
# CSS support for better integration with your web site
# Multi-language support with automatic user language detection. Including Right to Left scripting.
# Lightweight and fast
# Automatic browser detection and customization
# Image and file links upload and server repository browser.
# Complete toolbar customization
# Skins support
# Plugins support
The best things is that, FCKeditor is compatible with most of the internet browsers which include: IE 5.5+ (Windows), Firefox 1.0+, Mozilla 1.3+ and Netscape 7+.