In the New Testament the word 'prophesy' means to "speak before", or, "to speak for". It refers to one who speaks for God. (Holman Illustrated Bible Dictionary, [Nashville: Holman Bible Publishers, 2003]1333-1336.)
A puritan, William Perkins, defines prophecy like this;
"Prophecy is a solemn public utterance by the prophet, related to the worship of God and the salvation of our neighbors." (Perkins, William. The Art Of Prophesying, [Edinburgh: The Banner Of Truth Trust, first published in Latin 1592, English 1605, Reprinted 2002] 5.)He then tells the two parts of prophecy; 'preaching the Word and public prayer'. (Ibid. pg. 7)
Here's my take. Prophecy is speaking on the behalf of God to people, and on the behalf of God's people to God. Prophecy can only take place in a corporate setting. Prophecy takes place in churches where God speaks through His messenger to His people.
(There is also a spontaneous aspect as the Holy Spirit brings truth to light and mind. This aspect is not under consideration in this post, but will be in tomorrow's post.)
Prophecy is not mere preaching. It is not the explanation of a text or doctrine. Prophecy is preaching that takes place through the power of the Holy Spirit and is applied from the pulpit to God's people. The prophet gives God's people a message meant for them. He does not content himself with stating how Scripture applied to the Philippians, he shows how the same message to the Philippians is meant also for the hearers.
Prophecy is not mere praying. Prophecy takes place in prayer when the prophet assumes the role of intercessor. It is God's man going before God publicly, on behalf and in the presence of the people of God, as a representative, interceding for their sins, the congregation participating silently and acknowledging his prayer with the word, 'Amen'.
Of course the two great models of the office of 'prophet' are, in the Old Testament, Moses, and, in the New Testament, John the Baptist. Looking at these models we see the role of prophet displayed clearly. Although Moses and John the Baptist both predicted the future, this was not their primary role as prophets.
In Jesus Christ, we see the perfect Prophet, who represents both God perfectly and mankind perfectly.
If you are interested in these topics, Rob Wilkerson at Miscellanies On The Gospel has links to relevant sites as regards the ongoing debate.
Also, Phil Johnson posted some quotes by Spurgeon, along with the affirmation that Spurgeon was a cessationist.