Digital Marketing is the way to do all marketing things through digital media like electronic devices or internet. It uses different media and channels to promote business online. There are numbers of channels like SEO, SEM, Display Marketing, Social Media Marketing & SMS Marketing.
Yes, in present time people are more prone to use online media or internet rather than offline channels. Social media marketing helps in many ways to promote your business.
Social media marketing is a way to promote your business through social media channels like Facebook, Twitter, Instagram etc.