This website contains spoilers... lots of spoilers. You've probably heard the word before if you've done any browsing on the web, but what does it mean? Obviously we're not talking aerodynamics here, so what are these "spoilers" that people speak of? Well, put simply, spoilers are pieces of information that reveal some type of secret, such as a plot twist or the ending of a show.
A lot of times, websites will alert you that a spoiler is coming up in the text, so as to prevent people from accidentally reading them and revealing a secret before they've had a chance to watch for themselves. Sometimes, people will even even hide the spoilers by making the text the same color as the background, thus making it necessary for the visitor to select the text with their mouse cursor in order to make it visible. This site does something similar, but only on the forums. On all other pages of this site, spoilers are neither marked nor hidden. So this is your first, last, and only warning! If you don't want spoilers revealed, leave this site now!
Now, sometimes information that can be considered a spoiler is obvious, such as revealing the ending of a show or revealing that a good guy actually turns out to be the main villain. But other times, it's not so obvious. For example, in the first episode of Ranma 1/2, Ranma Saotome is revealed to be a boy who, when splashed with cold water, becomes a girl. Until this fact is revealed towards the end of the first episode, this could be considered a spoiler... except that this is the entire premise of the show, so typically it would not be considered a spoiler. In general, for anime in the US, the consensus is pretty much that if the information hasn't yet been shown in the US, then it is a spoiler.
So there you have it! Now carry on, carry on.