Mortgage Interest Rates are Important
First, a little review: Why are mortgage rates important?
For pretty much everyone, buying a home means borrowing money. Borrowing money means that you have to pay it back, generally by making regular payments over a period of time.
Since banks and mortgage companies are in business to make money, they charge people for loans. How much they charge is called the "interest" on the loan, and it is expressed as an annual percentage.
You borrow $100,000 at 5% per year for one year; at the end of the year you owe $105,000. If you borrow it for 30 years, at the end of the 30 years you owe $250,000 ($5,000 x 30 = $150,000 plus the original $100,000).
The whole system gets much more complicated when you pay the loan back monthly over time, but you get the idea: the lower the interest rate, the less you have to pay back, overall.
There are LOTS of mortgage calculators
available on the internet that can help you figure out what your payments on a home will be, figuring in credit scores, insurance, taxes, and other factors. Suffice it to say that a small increase or decrease in the interest rate can make a significant difference in your monthly payment.