Digital Marketing or Internet Marketing in simple terms is a marketing technique that promotes your business Online i.e. on the Internet through various platforms and resources provided by big giants like Google, Bing, etc.
Digital Marketing is a combination of different strategies implemented on various online platforms to reach the potential target audience based on the type of business or industry.
To name specific services for Digital Marketing would be tough as different businesses have a different target audience.
While, Search Engine Advertising like Google AdWords is helpful to reach the customers searching for your product or service on Google and is likely to buy it.
Social Media Marketing like Facebook, Instagram is important to create awareness and reach the audience which is particularly not searching for your product but might consider buying from you in the near future.