What is the purpose of system table master..spt_values and what are the meanings of its values?

Question

What is the purpose of system table master..spt_values?
Why was it provided and how one should use it?

What are the meanings of its type, low, high values?

Answer 1

One usage, definitely not its primary usage, is to generate a series of numbers:

--Generate a series from 1 to 100
SELECT
    TOP 100
    ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) AS RowNum
FROM master.dbo.spt_values ORDER BY RowNum