According the their article,
"Often the word “ironic” is misused to remark on a coincidence, such as “This is the third time today we've run into each other. How ironic.”
It is also mistakenly used to describe something out of the ordinary or unusual: “Yesterday was a beautiful, warm day in November. It was really ironic.”
And, unfortunately, it is sometimes used to simply emphasize something interesting. For example, “Ironically, it was the best movie I've seen all year!”"
Another important misuse of "ironic" is when it is used incorrectly in the place of the "sarcasm". The only time when something is really ironic, is when it is the exact opposite of it's literal meaning. A statement such as, "It's been such a good day" would be ironic if you were using it to describe the day you were late to work, wrecked your car, and got soaked in the rain. A sarcastic statement would be something like saying something like, "Wow, your shirt is so nice" to someone who has theirs caught on a nail and ripped, and is obviously embarrassed by it. The main difference between irony and sarcasm, is that with sarcasm, you are deliberately trying to taunt, harass or make fun of someone, while with irony you are not.
To learn more about irony and the different types of it there are, you can go to hotword.dictionary.com/ironic/.