The question is a deep one!
It has far reaching effects, but it has a somewhat simple answer!
The Book of Mormon (Moroni 7:16-17) talks about The Light of Christ which is given to every man, saying:
That which is of God inviteth and enticeth to do good continually; wherefore, every thing which inviteth and enticith to do good, and to love God, and to serve him, is inspired of God.
But whatsoever thing persuadeth men to do evil, and believe not in Christ, and deny him, and serve not God, then ye may know with a perfect knowledge it is of the devil; for after this manner doth the devil work, for he persuadeth no man to do good, no, not one.Some would call it a conscience, I would personally consider it more of that natural tendency within all of us to follow and go towards light and truth and ultimately to follow Jesus Christ. When we are faced with a choice, there are always good and bad choices (or good and better... either way, im not picky). The Holy Ghost in those times will provide additional guidance and support to those who seek it in such times.
So the short answer to the question, "is it a prompting and should I follow it?" is based off a quote from President Hinckley:
“That’s the test, when all is said and done. Does it persuade one to do good, to rise, to stand tall, to do the right thing, to be kind, to be generous? Then it is of the Spirit of God. . . .If it invites to do good, it is of God. If it inviteth to do evil, it is of the devil. . . . And if you are doing the right thing and if you are living the right way, you will know in your heart what the Spirit is saying to you. You recognize the promptings of the Spirit by the fruits of the Spirit—that which enlighteneth, that which buildeth up, that which is positive and affirmative and uplifting and leads us to better thoughts and better words and better deeds is of the Spirit of God”The whole reason this blog is called "A Spark Of The Light Of Christ" is because I know that this is within all of us and that we get little flashes of goodness and inspiration to do and choose right, no matter who or where we are. Furthermore, as we courageously follow those things we think and know to be good, we will be able to distinguish more perfectly the promptings we receive and increase in our ability to follow with exactness. Whether you are using baby steps or taking strides as a spiritual giant, the filter of the mind (does it persuade to do good?) and the heart (does it feel right?) use the same formula.