Salesforce is great for small business!
Salesforce is a powerful customer relationship management solution for small business because it lets sales, support and operations associates all work in the same system. When associates can look up order history, pending sales, notes and support tickets all in the same place then they can better help customers with whatever they need. Keeping customer information together in one place enables great customer experiences, as shown in this Trailhead module.
The consistency of the Salesforce user interface, with tabs, list views, Chatter comments, related lists and details, means that associates don't need to learn a new system to help in another department.
There are great add-ons, too, as this Lead to Cash Trailhead shows.
And since Salesforce has plenty of happy enterprise customers you know your solution can scale up and keep running no matter how much you grow.