This psalm, like some others, is entitled "a psalm or song;" that is, it so far combined the properties of both a "psalm" and a "song" that it might be called by either name. See the notes at the title to Psalm 65:1-13. The phrase "for the sons of Korah" may mean, as in the margin, "of the sons of Korah." See the notes at the title to Psalm 42:1-11.
The occasion on which the psalm was composed is unknown. The design of the psalm is obvious. It is to exalt Zion as a place to dwell in, and to state the privileges or advantages of having been born there; the honor of such a birth, and the benefit which would he connected with it, from having been brought early under the influence of the true religion, and from having been trained up amidst its institutions. The practical truth which is suggested by the psalm is the honor and benefit of having been born in a land where the true religion prevails; of having been born in connection with the church; of having been early devoted to God; and of having had the benefits of a religious training. The foundation of what is said in the psalm is the honor which we naturally associate with the idea of birth; birth as connected with a family of distinguished worth, wealth, or rank; birth as connected with a particular country, city, or town.

The nature and glorious privileges of Zion and Jerusalem, Psalm 87:1-3. No other city to be compared to this, Psalm 87:4. The privilege of being born in it, Psalm 87:5, Psalm 87:6. Its praises celebrated, Psalm 87:7.
The title, A Psalm or Song for the sons of Korah, gives us no light into the author or meaning of this Psalm. It begins and ends so abruptly that many have thought it to be only a fragment of a larger Psalm. This opinion is very likely. Those who suppose it to have been made when Jerusalem was rebuilt and fortified, imagine it to have been an exclamation of the author on beholding its beauty, and contemplating its privileges. If this opinion be allowed, it will account for the apparent abruptness in the beginning and end. As to its general design it seems to have been written in praise of Jerusalem; and those who are for mystic meanings think that it refers to the Christian Church; and, on this supposition it is interpreted by several writers, both ancient and modern. To pretend to have found out the true meaning would be very absurd. I have done the best I could to give its literal sense.

INTRODUCTION TO PSALM 87
A Psalm or Song for the sons of Korah. Whether this psalm was composed by David, in a view of the temple to be built by his son Solomon; or whether by one that returned from the Babylonish captivity, who wrote it for the comfort of those that wept at the laying of the foundation of the second temple; it seems evident that the subject matter of it is the church of God in Gospel times, and especially in the latter day glory: the title in the Syriac version is,
"concerning the redemption of Jerusalem.''.

(Psalm 87:1-3) The glory of the church.
(Psalm 87:4-7) It is filled with the Divine blessing.

The City of the New Birth of the Nations
The mission thought in Psalm 86:9 becomes the ruling thought in this Korahitic Psalm. It is a prophetic Psalm in the style, boldly and expressively concise even to obscurity (Eusebius, σφόδρα αἰνιγματώδης καὶ σκοτεινῶς εἰρημένος), in which the first three oracles of the tetralogy Isaiah 21:1, and the passage Isaiah 30:6, Isaiah 30:7 - a passage designed to be as it were a memorial exhibition - are also written. It also resembles these oracles in this respect, that Psalm 87:1 opens the whole arsis-like by a solemn statement of its subject, like the emblematical inscriptions there. As to the rest, Isaiah 44:5 is the key to its meaning. The threefold ילּד here corresponds to the threefold זה in that passage.
Since Rahab and Babylon as the foremost worldly powers are mentioned first among the peoples who come into the congregation of Jahve, and since the prospect of the poet has moulded itself according to a present rich in promise and carrying such a future in its bosom, it is natural (with Tholuck, Hengstenberg, Vaihinger, Keil, and others) to suppose that the Psalm was composed when, in consequence of the destruction of the Assyrian army before Jerusalem, offerings and presents were brought from many quarters for Jahve and the king of Judah (2-Chronicles 32:23), and the admiration of Hezekiah, the favoured one of God, had spread as far as Babylon. Just as Micah (Micah 4:10) mentions Babylon as the place of the chastisement and of the redemption of his nation, and as Isaiah, about the fourteenth year of Hezekiah's reign, predicts to the king a carrying away of his treasures and his posterity to Babylon, so here Egypt and Babylon, the inheritress of Assyria, stand most prominent among the worldly powers that shall be obliged one day to bow themselves to the God of Israel. In a similar connection Isaiah (Isaiah 19:1) does not as yet mention Babylon side by side with Egypt, but Assyria.