Until now combining many columns into a single one was a cumbersome process. 
Here is a formula seen in the web to stack columns with native Google Sheets™ function:
=QUERY(ArrayFormula(SPLIT(TRANSPOSE(SPLIT(textjoin("-",TRUE,TRANSPOSE((A1:H1&","&A2:H5))),"-")),",")),"Select * where Col2<>''")

Not very comprehensive, isn't it?

Use =𝗦𝗧𝗔𝗖𝗞𝗔𝗥𝗥𝗔𝗬(𝘆𝗼𝘂𝗿_𝗮𝗿𝗿𝗮𝘆) and stack your columns or rows instantly wherever you need it in your spreadsheet. Without altering the initial array.


▶︎ 𝗖𝗛𝗘𝗖𝗞 𝗢𝗨𝗧 𝗢𝗨𝗥 𝗗𝗘𝗠𝗢
https://docs.google.com/spreadsheets/d/1YBMUfJPbePUffEddtpzL2nMstkHzCcf_tjbKu6LR5kI/

𝗠𝗢𝗥𝗘 𝗢𝗣𝗧𝗜𝗢𝗡𝗦...

✓ Use =STACKARRAY(your_array, TRUE) in order to remove all blank cells

✓ Stack row by row instead of column by column =STACKARRAY(ref_to_your_array, , TRUE)

✓ To merge an array with unique values only, use =UNIQUE(STACKARRAY(your_array))

✓ To sort the resulting column, use =SORT(STACKARRAY(your_array))


Find out more...
https://nodatanobusiness.com/add-ons/stackarray