Most businesses have a certain objective in mind when creating a website. The objective depending on the business sector can be to generate more leads, increase product sales, find local customers or sell services. Merely making a website does not help to achieve these objectives.
This is where SEO is helpful as it allows customers to find your business with the right keywords instead of you finding your customers. It also saves cost as you do not have to employ professionals for outbound marketing activities like tele-calling, social media campaigns etc.
Since SEO is inbound, you will find only targeted visitors coming to your website through google search and hence are more likely to call you for business.