What is it and does it replace my website and the need for press releases?

Social media is a good way to get new information out to the world, fast.

Will it replace press releases?  Possibly in some instances but most likely not and both would be better anyway.  Press releases are more formal and usually have more detail than a Tweet for example.  Social media posts are informal and short.

Will it replace your website?  No.

Your website should tell your visitors about your company, products and services and anything else you think will help to get your customers to want to do business with you.  Put information on your website about why the visitor needs what you sell and don't forget to tell them how to get it.

Social Media is being used to get the word out quickly.

The Twitter or Facebook sites should give current information on news items or a brief comment on current events for example.  Use Social Media to drive traffic back to your website where the visitor can get in-depth detail or information on your news item.

Your website and your social media efforts should work together to generate interest and business for you.  Think of social media as another part of your online team the same as newsletters and advertising.