Fresh content can be almost anything. It can be regular blog posts related to the topic of your site. It can be photographs of the work you've done or events at which you've participated. It can be announcements of new products or services you've added to your offerings. It can even be coupons and specials that you offer on your services. New content can have purely commercial intent, although you'll get more mileage if most of your new content is meaningful to users.
When a website remains static, the search engines recognize that nothing has changed, and the spiders will visit at less frequent intervals. The value of the site as a whole will diminish in the eyes of the search engines. New content sends a completely different signal. New content serves as a signpost that your site is an active and engaging community. The search engines will send spiders more often to crawl your site and your rankings will rise.
Remember that you can schedule content to...