Credit scores are pulled from a statistical analysis using credit reports that come from credit bureaus. Credit scores are important to lenders because it lets them know who will be risky to lend money to, and who wouldn't be as risky. A risky person would be someone with a low credit score since a low credit score indicates a lack of payment (in a lot of cases). In that case, even if a lender qualified that person for a loan, they would give them a very high interest rate as a way to protect themselves in case the person failed to make the payments after a while, thus failing to pay back the lenders in full what is owed to them.
It is important to have a good credit score because your credit score is what determines what you qualify for, and at what interest rate. Lenders for loans are not the only ones that use credit scores. Lenders for banks and credit card companies also use credit scores to make their decisions. Other companies that may loan money out such as mobile phone companies also check credit scores. Even insurances many times will check your credit score. Almost anywhere you go these days you are getting your credit checked unless you pay for everything in cash.
It is therefore important to check your credit score often to ensure that your credit remains good. If your credit is not very good, it is wise to start on repairing your credit right away. You can start yourself by going through your credit reports and looking for anything that may be questionable. If you are having a hard time making your payments, you can try to figure out ways to reduce your payments. If you need help, there are many credit repair companies that will help you to boost up your credit score.