The Third Trimester

So I've learned that depending on what book or internet site you are following there are some discrepancies as to when someone completes one month and moves to the next. According to www.epregnancy.com the third trimester begins at week 27. According to "What to Expect When You're Expecting" the third trimester begins at week 28. Tomorrow marks week 28 for me so I guess I can "officially" say that I've made it to my last trimester and am in the home stretch.