Poqery created the ability to Highlight Questions and Answers because often users will post a response only to find it buried under an avalaunch of other questions and answers asked afterwards!
There is nothing worse then spending 30 minutes writing out a detailed question, only to have it down 10th place in the list of questions because 10 other (less serious!) questions have been asked after yours!
This feature allows you to make sure your question has the best chance to be answered or alternatively your answer has the best chance to be read and designated the "best answer".
So how does it do this? There are 3 benefits to highlighting a Question:
Your highlighted question is given a new and more prominent look to stand out from other un-highlighted questions
When you highlight a question it is given sort-order priority. That means it will always appear above unhighlighted questions until the highlighting period runs out. Only highlighted questions which have more time remaining will appear above your queestion.
50% of the Bonus Chips (BC) used will then appear as a reward for the Best Answer. So if you use 1000 BCs to highlight then 500 of those BCs will appear as a reward. That reward is given out when you choose the best answer.
Highlighted answers work in a similar way but no Reward is generated. Highlighting an answer gives it the best chance possible of being read and possibly designated as the best answer!