A good example is Facebook Custom Audiences. Within this Facebook supports email targeting, the ability to upload customer email addresses and then target those users on Facebook with tailored ads. This lets you micro-segment based on your existing customer database. One application is customer loyalty marketing, promoting offers to existing high value users via Facebook ads.
Search engine marketing encompasses a range of activities all centred around making your website more visible when someone uses a search engine. If someone is looking for your business on the internet, it is vital your website appears prominently in the search engines’ results pages, or it will never deliver the value to your business that today’s economy demands.
Of course, there is a lot more that needs to be considered but this is a simple example of how all of these things work together. I would recommend having no less than one page for each step of the organic marketing plan if you are a small business. The larger your business the more planning that you should do. If you do not think through all the details you will miss something that will cost you.