Also known as the serial comma, which is a comma immediately preceding the conjunction and, or or nor. Even though Strunk and White calls for always using the serial comma, I’ve been leaving it out to save space and because I thought it superfluous.
This statement for The Times [London] has changed my mind:
… highlights of his global tour include encounters with Nelson Mandela, an 800-year-old demigod and a dildo collector.
Unless Nelson Mandela was a dildo collector and also an 800-year old demigod, the serial comma should be inserted after the word demigod in that sentence.
I’m going to try to remember to always use it from now on. I probably won’t remember. Habits once established are powerful things. I just moved to a new house 10 miles from my old house. Returning from a weekend out of town I recently drove all the way to the old house and was about to pull in the driveway before realizing I had driven to a house I no longer live in.