To most home owners it's a surprise that gutters need to be cleaned. They accumulate all sorts of debris. Most first falls on the roof and makes its way from there into the gutters. The downspout clogs, and before you know it the gutter is overflowing.
Clogged gutters trap water near the foundation
Overflowing gutters a the number one cause for wet basements. Your roof funnels water that would normally fall on the whole area your roof covers to a limited number of drains. If one of those overflows, the water finds it way into the basement.
In colder climates it's important to keep the gutters ice free. In the early spring or late fall you do not want ice to form in the gutters. Icicles will form and any snow that slides off the roof could take your gutters with it.
How to clean gutters
Cleaning gutters is very simple do to, but tedious. Get on the roof or a ladder and lift the debris out of the gutter. There are a number of tools for this task. I have tried a few. Eventually I always revert to using my hands. There are gutter cleaning robots, which I consider pure garbage.
If you have access to a garden hose, you can by a gutter cleaning attachment. This tool allows you to clean the gutters with a jet of water from the safety of the ground. Keep in mind that this tool will blast the debris all over your front yard. I consider this a deal breaker.
The most important thing about cleaning gutters is personal safety. You will be working on your roof or on a ladder. First and foremost make sure you will not fall. Do what is necessary to be safe. On a steep roof a ladder is probably the best choice. On some roofs the best choice might be calling the professionals (people who take the risk for you).
Don't clean gutters, if they are not dirty
Don't fall for companies selling you regular gutter cleaning services. Gutters do not need to be cleaned every month, not even every half year. They need to be cleaned when they are clogged.
In my case one corner of the house needs to be cleaned monthly. The middle is ok for up to a year, and the far side for up to 4 months. In the fall, when there are a lot of leaves around, cleaning may be needed more often. Get to know your house. It can save you a lot of money in unnecessary service fees.
My home is located in the middle of several evergreen trees. I pay the price for it. The gutters clog so often I find myself on the roof about once a month. As much as I hate clearing them, I know the work needs to be done. Next week the Seattle home is coming to town. I am going to search for a gutter guard product, such as leaf guard.