The CONTAINSfunction in Tableau is used to check if a specific substring exists within a string and returns a Boolean value (TRUEor FALSE). This function is ideal for identifying whether a particular sequence of characters is present within each value of a column. RTRIM removes trailing spaces, SPLIT divides strings based on a delimiter, and ENDSWITH checks if a string ends with a specified substring, but none of these functions return a Boolean value indicating the presence of a substring.