something (such as a headline) designed to make readers want to click on a hyperlink especially when the link leads to content of dubious value or interest (from Merriam-Webster Online Dictionary)
So, what does Clickbait look like???
Offers easy fixes for your problems.
Fixes problems you didn't know you had.
Offers you a way to test your intelligence (or prove that you aren't an idiot).
Temps you with useless information/knowledge.
Offers potential gore or surprise.
Easy to avoid clickbait headlines,..
...ones that will rarely actually "blow your mind".
You won't believe it! And you won't or shouldn't.
Just. Don't. Click.
Many reputable news outlets sometimes use a form of Clickbait, after all, they are fighting for your attention. But those sites that regularly use these, especially extreme forms of it, should be avoided.
More: Some additional sources: