I have asked a series of questions recently about the superscripts at the top of the Psalms.* They tend to include technical notes about performance, (possible) allusions to authorship, notation of the context in which they were written, and probably sometimes other things. They seem to be fairly dense with uncertain terminology.
My understanding is that these headings aren’t original to the psalms. They refer to the author in the third person at times, and many of them re-use similar phrases, as if they were added at the same time by the person compiling them. They’re there in the LXX (albeit sometimes oddly translated), so they must be fairly early additions. I realize there is controversy about which psalms were written when, but is there any consensus about when the superscripts (please correct me if there’s a better term) came about?
*I linked to a set of my own questions there because I haven’t found other questions about this on BH.SE. If I've missed any, please add them.