If you're here...
Chances are, someone sent you here because someone feels you've grossly misused the word "ironic" in conversation.
What Irony Is
Irony is the use of words in a way to conceal true intention with literal intention. More clearly, irony is when you say one thing but mean another. Much subtext, many puns, and quite a bit of sarcasm and slander are dependent on irony. When someone gets a new awful haircut and asks you what you think, and you say that it's "a real good 'do'" (using "do" to mean she was done over, and didn't get her money's worth,) you've used irony - whether or not it's obvious probably determines whether you get yelled at.
Similarly, if a plot involves a famous person with a dirty secret, and the famous person asks another character if a third person knows who they are, then a response "Oh, she knows exactly who you are" to answer what the famous person would want to hear but really to mean "she and I know your secret and you're not fooling us" would be the use of irony.
What Irony Isn't
If person A does thing X, and somehow it comes back and bites them in the ass, that is not ironic.
If something happens to someone which would have been preventable had they not done some awful thing they did, that's not ironic.
There is no irony in catching someone doing what they told others not to do, nor is there irony in something happening after someone suggested it wouldn't/couldn't.
There is no irony in someone aspiring to better someone else by improving one facet and ending up with an even lesser result.
There is no irony in trying to prevent something and thereby accelerating or worsening it.
