Prayer of the Hours

Q: When do we say the Little Office and what is the meaning of the various hours?

A: The meaning of the Prayer of the Hours (the Little Office of the Blessed Virgin Mary is an expression thereof) is to sanctify the whole day. Thus, the hours of the office are distributed over the whole day. Here is how the classical prayer times were scheduled:

Matins - 3 am (or before the beginning of the day)
Lauds - 6 am (beginning of the day)
Terce - 9 am
Sext - 12 pm (mid-day)
None - 3 pm
Vespers - 6 pm (at the end of the workday)
Compline - 9 pm (before going to bed)

The abbreviated form is limited to two hours: Lauds and Vespers, understood as morning and evening prayer.