A captivating closing is a summary of your presentation. However, it expresses your take-home point in a way that is memorable for the outstanding way in which it was presented. A captivating closing does at least one of four things: Provokes the audience, stimulates the audience, motivates the audience or electrifies the audience. Peter Jeff, in "10 Ways to End Your Speech with a Bang," recommends "Instead of firing off a perfunctory 'thank you,' consider launching fireworks of final passionate thoughts from the podium."
The best closing in the world cannot compensate for a poor presentation. It cannot counteract the effects of an unremarkable speech or paper. Your presentation must be infused with stimulating material. If it's an oral presentation, practice your delivery until you are thoroughly comfortable and can project confidence and professionalism without relying on your notes. Don't be long winded. It doesn't matter how captivating your closing is if people are sleeping through it.
The Advanced Public Speaking Institute advises that you issue a call to action. One way to ensure an unforgettable closing is to stir the audience to fight hunger, combat homelessness, protest illegal activity, write their congressman, start a grassroots effort or even lose 10 pounds. A captivating closing should motivate the audience to do something.
In "20 Ways to End a Speech," Jim Peterson recommends that you close by shocking the audience with a startling statistic or fact that will jar them out of complacency. For example, a closing like, "within the next five years, half of the people in this room will be uninsured" (or out of work, or homeless) will surprise and astonish your audience and leave a lasting impression.