Many companies are now using social media to marketing their business. There is a number of popular social media sites that you can use, but the most popular ones for businesses are usually Facebook and Twitter.
If you have a business that deals direct with the public then social media is especially important as you can connect with individual users on a personal basis. If you owner services to other businesses then social media can still help and should be a part of your marketing strategy. Business to business companies can help establish and build a brand using the social media sites.
The beauty of social media, is that much of it is free, it just takes time which some businesses simply do not have. If this is the case, you could consider hiring a social media marketing company to assist you with the creating of content and posting / replying to social media interaction.