Marriott sells the use of week 53 in those years when it occurs. For this year, generally, it will be weeks that start on Sunday, December 31. You can see whether your resort has a week 53 for a particular year by looking at the bottom of the calendar for that resort located on the MVCI website.
None of us own week 53. Marriott reserves such weeks for its own use and typically sells them.
Until 2005, Marriott put them on sale to all owners at the same time. That created a nightmare as many, many people were not able to get through to Marriott on the morning we could first purchase the use of such a week. In 2005, Marriott offered such weeks first to those who owned a significant number of weeks, made frequent referrals or in some other way were considered one of Marriott's best timeshare customers. As the year went on, Marriott offered unclaimed weeks to more and more timeshare owners until all owners ultimately had a chance to get a week.
In prior years, an owner could purchase a week at his/her home resort. In 2005, owners were not limited to purchasing at their own resorts. In prior years, the cost for a week was typically equal to one year's MFs at the resort. In 2005, the cost for a week was typically several hundred dollars higher.
Thus, the "gift of time" is the opportunity to use (for a fee) a week in addition to what you own.
And now, we're waiting to see what form the 2006 program will take.