A cron expression consists of five individual parts (That is the basic version. Some cron expressions support additional values).
Part
Allowed Values
Minutes
0-59
Hours
0-23
Day of month
1-31
Month
1-12
Day of week
0-6 (0 = Sun, 1 = Mon, ...)
In addition to the above values the following characters can be used.
Character
Meaning
*
Any value e.g. * as the value for Hour will select all the possible values 0,1,2,..,23 "every hour".
,
value list separator e.g. 0,30 as the value for Minute will select 0 and 30 "every half hour".
-
Range of values e.g. 1-5 as the value for Day of week will select Monday thru Friday
/
step values e.g. */3 as the value for Month will select Jan, Apr, Jul, Oct. Writing "1,4,7,10" would yield the same result.
15 1 * * * every day at 1:15 am
0 8-17 1-5 * * Monday thru Friday, once every hour between 8am and 5:59pm
0 5 1 */3 * at 5am on the first day of every third month of the year (Jan, Apr, Jul, Oct)
0 0 1 1 * start of the year
*/5 3-14 * * 6 every five minutes between 3am and 2:59pm only on a Saturday
Cron expressions are widely used. To get more detailed information those links might be helpful