Temptation is defined as, a desire to do something, especially something wrong or unwise. This could be seen as anything, however a common form of temptation is, "do not..." The minute someone says you can't do something, it's all of a sudden the only thing you want to do. A great example of this is from popular american sitcom series, How I Met Your Mother. In their episode Lobster Crawl, Robin is told that she can no longer have lobster due to her allergies. Now, Robin has a sudden huge desire to consume Lobster. The temptation was too real.
Temptation is seen with in all throughout Shakespeare's play, Macbeth. It starts in Act 1, scene 3 when the witches first tell Macbeth and Banquo the prophecy. The pair listen to the tantalizing words of the witches, foretelling of the success of themselves and their descendants, "Thou shalt get kings, through though be none: So all hail Macbeth and Banquo!" (Macbeth 1.3). Seeing as this is only a prophecy, that doesn't mean it has to necessarily come true. That's why Banquo makes nothing of it. Macbeth on the other hand is fixated on their words.
The witches' prophecy is a great example of temptation in Macbeth. As stated before, they told a prophecy, a mere prediction of the future. This doesn't mean that their fortunes are set in stone. However, the idea of a royal crown sparks something within Macbeth. The idea of one day being ruler being a future possibility is very alluring to him. This is what begins his drive on the highway to hell.
There are many consequences for a person who decides to turn evil. For example, they're no longer good. Along with their, they trade in their sanity and morals for their dark desires. In no way shape or form do the witches tell Macbeth to kill for the throne, he does that on this own accord (with the help of some serious Lady Macbeth-thing). The temptation for the crown and power for caused Macbeth to throw away his moral compass and murder (the now) late King Duncan and his guards (Macbeth 2.3). Later on in the story, Macbeth makes no hesitation in killing his bff Banquo to secure his power (Macbeth 3.3). It's okay, who really needs a moral compass when you can be a tyrant anyways?
Along with a loss of morals, Macbeth is slowly driven to insanity. After the impulsive murder of his friend, Macbeth sees his ghost appear before him at his house! The estranged ghost of Banquo decides to pop into Macbeth's dinner party (as any good friend would), but the thing is only Macbeth can see him (Macbeth 3.4). If that's not insanity, then I don't know what is. The temptation of power has slowly decayed Macbeth's sanity to the point where he's seeing ghosts.