Search engines like domains that continually produce content. It makes sense. As a search engine, you are going to want to send your users to the most relevant, most up-to-date information available on the Internet. If you consistently send your users to stale, out-of-date, irrelevant information, they are likely to go try out the competition next time they perform a search.
One of the most effective and easy ways any business can ensure that their website demonstrates this continuous activity is to write a blog. Writing content about the type of work your business does helps establish your domain as an authority on that subject.
Say you are a company that sells gardening supplies (services apply to this example as well), and you want to rank well in search engine results pages for the keyword ‘watering systems.’ In order to show up in search results, your site is going to need to have relevant information about water systems on it.