Counting number of occurrences in column?

Question

What would be a good approach to calculate the number of occurrences in a spreadsheet column? Can this be done with a single array formula?

Example (column

Answer 1

Put the following in B3 (credit to @Alexander-Ivanov for the countif condition):

={UNIQUE(A3:A),ARRAYFORMULA(COUNTIF(UNIQUE(A3:A),"=" & UNIQUE(A3:A)))}

Benefits: It only requires editing 1 cell, it includes the name filtered by uniqueness, and it is concise.

Downside: it runs the unique function 3x

To use the unique function only once, split it into 2 cells:

B3: =UNIQUE(A3:A)

C3: =ARRAYFORMULA(COUNTIF(B3:B,"=" & B3:B))