Digital marketing is  

“…an umbrella term for the targeted, measurable, and interactive marketing of products or services using digital technologies to reach and convert leads into customers and retain them. The key objective is to promote brands, build preference, engage with customers and increase sales through various digital marketing techniques. It is embodied by an extensive selection of service, product, and brand marketing tactics, which mainly use the Internet as a core promotional medium, in addition to mobile and traditional TV and radio.”
Read more: https://www.digitalimpact.co.uk/what-is-digital-marketing/

Digital marketing is about reaching out to consumers using digital channels such as internet, mobile phones and social media. The goal is to promote a brand by using different digital means.

Digital marketing centers around the Internet which can be used both to push a message to someone like email to introduce a brand as well to “pull” content serving a banner advertisement. Digital marketing, therefore, can be thought of as the combination of push and pull Internet technologies to execute marketing campaigns.

Because it is digital, a reporting engine can be integrated within a campaign to gather data that shows how the campaign is performing, such as what is being viewed, how often, how long, as well as other actions such as responses rates and purchases made. Depending on how the digital market is implemented it can generate different data that can be analyzed. 

Digital Marketing is new and has lots of room for innovations. Innovations such as targeting right consumers depending on their location, time, lifestyle and other. The ultimate goal is to show right brand to right people.

http://www.captora.com/digital-marketing/digital-marketing-definition

Digital marketing extends beyond internet marketing to include channels that do not require the use of the internet. It includes mobile phones (both SMS and MMS), social media marketing, display advertising, search engine marketing, and any other form of digital media.'

http://lexicon.ft.com/Term?term=digital-marketing&mhq5j=e7

Digital marketing is often referred to as 'online marketing', 'internet marketing', 'web marketing' or even 'data driven marketing'. Digital marketing is an umbrella term for the marketing of products or services using digital technologies, mainly on the Internet, but also including mobile phones, display advertising, and any other digital medium.
https://www.linkedin.com/pulse/definition-digital-marketing-how-applies-you-kevin-krejca

Digital marketing is the process where it utilizes multiple channels, for example such as content marketing, influencer marketing, SEO, social media, and online advertising to help brands/business, communities, and people to be able to connect with each other and potential customers.

http://www.toprankblog.com/2014/07/digital-marketing/

The marketing of products or services using digital channels to reach consumers. The key objective is to promote brands through various forms of digital media.

Digital marketing extends beyond internet marketing to include channels that do not require the use of the internet. It includes mobile phones (both SMS and MMS), social media marketing, display advertising, search engine marketing, and any other form of digital media.

Most experts believe that 'digital' is not just yet another channel for marketing. It requires a new approach to marketing and a new understanding of customer behaviour. For example, it requires companies to analyse and quantify the value of downloads of apps on mobile devices, tweets on Twitter, likes on Facebook and so on.
http://lexicon.ft.com/Term?term=digital-marketing

Digital marketing extends beyond internet marketing to include channels that do not require the use of the internet. It includes mobile phones (both SMS and MMS), social media marketing, display advertising, search engine marketing, and any other form of digital media.

http://lexicon.ft.com/Term?term=digital-marketing

Digital marketing extends beyond internet marketing to include channels that do not require the use of the internet. It includes mobile phones (both SMS and MMS), social media marketing, display advertising, search engine marketing, and any other form of digital media.

http://lexicon.ft.com/Term?term=digital-marketing&mhq5j=e6