It is good to use a calendar.
Carrie has been sent an invitation to join her friend Gia for a birthday brunch on the 27th of the month.
Carrie wants to RSVP to the brunch.
Carrie RSVP's to the brunch and marks it on her calendar.
Carrie RSVP's to the brunch without noting the date on a calendar.
Carrie makes the brunch on time to celebrate Gia's birthday.
When the 27th comes around, Carrie completely forgets about the brunch and misses Gia's birthday celebration.