Some businesses use social media a lot as a form of marketing to help their business. Social media sites can be used in a number of ways for businesses such as to promote a product or service, run competitions, build traffic to a website or as another way of getting in touch.
Some businesses will think that by using social media they will suddenly see an increase in sales that comes directly from the social media sites, but this is not always the case.
Very often social media marketing can be used more to build up your brand, engage with your customers and build up trust. You may not actually make sales or take enquiries through your social media site, but you can often improve the likely hood of someone seeing your business and either clicking through to your website or sharing your details to someone else they may think would be interested.
If you use a stats package such as Google Analytics, you can often track how many referrals you are getting from the social media sites. Although not all of these may turn in to sales, all traffic can help.