The /* and */ delimiters may be used to set off a comment in SQL*Plus. Comments entered this way may span multiple lines. If you use /*...*/ in a script file, the comments will be displayed on the screen when the script is executed. Chapter 4, talks about the different ways to enter comments in SQL*Plus.
/*comment_text
comment_text
comment_text
*/
where:
Marks the beginning of the comment.
Is the text making up the comment.
Marks the end of the comment.