These words you see in the brackets (ex: quote, b, u...) are sets of html tags known as BB code. They are based on HTML, and allow you to format your messages in the forums. Not all forums allow all the tags. Here is a list of codes that are useable in the Spymac Forums:

url - This will make your link "clickable" (this is usually done by default whenever a URL is suspected).
Usage: [URL=http://news.google.com]Google News[/URL]

b - This will make the text bold.
Usage: [b]Make this bold[/b]

i - This will italicize the text.
Usage: [i]Italicise this text[/i]

u - This will underline the text.
Usage: [u]Underline this text[/u]

color - This will add color to the text.
Usage: [color=red]This text appears red[/color]

list - This adds a bulleted list.
Usage: [list]Bulleted list follows[/list]

code - This will add some code into your post. The portion of text within these tags will appear within a box with dotted borders and normal white background.
Usage: [code]Put this text[/code]

quote - This will put text in special grey box. This is used when you wantto reply to an earlier post and want to quote that person. The portion of text within these tags will appear within a box with dotted borders and grey background. You can always achieve this by clicking the "Quote" button in the thread.
Usage: [quote]quoted text follows[/quote]

size - This can change the size of you written text.
Usage: [size=3]Changed Size[/size]

font - You can change your written text into any font.
Usage: [font=Arial]Changed Font[/font]

img - you can place a URL to an image in the "img" to upload from that URL.
Usage: [IMG]http://arnieshwartz.spymac.com/pics/daisy.jpg[/IMG]

While most of these options are already available to you by just clicking a button in the "reply" in the Spymac forums, by knowing these codes you can use then use them in the "Quick Reply" when the option buttons are not available. The usage shows you how to type them into your post.

You can add several BB tags in one text statement. Only remember to close them in the order in which you opened them.
Usage: [b][u][i]Bold, underlined, italicised text[/i][/u][/b]

Invisible Ink

Invisible ink is a special way of hiding our post, or part of it, so that only those who you've given access in your Friend Manager can view it. It's used to convey messages to friends who're reading the same thread as you are, while not interrupting the normal discussion that's going on.

Usage: [hide]Hidden message[/hide]

A post that is wholly written in invisible ink will not be vieweable to those who're not on the access list of the poster. The post will appear to read "Invisible Agent" to them.