What CSV is
CSV is a text file where each line is a row and commas separate the fields. There is no type system, no formatting and no second sheet. Every value is text until something downstream decides otherwise.
Almost every database, analytics tool and spreadsheet can read and write it, which is why exports default to it.
What Jira is
Jira wiki markup uses double pipes for header cells and single pipes for data cells.
Jira issues, comments and descriptions.
What changes when you convert CSV to Jira
Reading CSV means deciding three things the file does not state: which character separates fields, how quotes work, and what encoding the bytes are in. Tablizer sniffs the delimiter from the first few lines, handles quoted fields containing commas and newlines, and reads the file as UTF-8.
Empty cells are filled with a single space, because a Jira row with two adjacent pipes collapses the column and shifts everything after it.
What carries over from CSV to Jira
One property of the CSV has no home in Jira, and it is worth knowing which before you convert.
A line break inside a cell ends the row in Jira, so line breaks are replaced rather than carried through.
Jira marks its header cells differently from its data cells, so the first row is written with that marker.
The identifier 007 comes out of the Jira as 007. Reading it as a number would have made it 7, and an id that changes value is worse than one that stays text.
The role "Analyst, data" survives with its comma, in one cell rather than split across two. That is the first thing to check in any converted table, and the usual place a Jira file goes wrong.
The quotes around Jonah "Jo" Pryce are left as a plain quote character in the Jira.