Psalm 150 concludes not only the entire psalter, but also the last five psalms that begin and end with Praise the LORD!, or in Hebrew: Hallelujah! Although it is brief, this psalm gives a clear what, who, why, where, & how.
What? Praise – give glory to – the LORD, YHWH, the ever-existing God.
Who? Everyone – everything that has breath (v. 6).
Why? For the LORD’s mighty deeds, and the abundance of His greatness (v. 2).
Where? In His sanctuary and in His mighty expanse, or firmament – essentially everywhere (v. 1)!
How? With all manner of musical instruments and dancing; i.e., with all we have, including our breath (vv. 3-6).
Although no specific when is given, the song suggests that there are no limits – Praise the LORD any time and all the time!