2. What is Digital Marketing?
Digital marketing (also known as data-driven 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.
Digital marketing's development since the 1990s and 2000s has changed the way brands and businesses utilize technology for marketing. As digital platforms are increasingly incorporated into marketing plans and everyday life, and as people use digital devices instead of visiting physical shops, digital marketing campaigns are becoming more prevalent and efficient.
Digital marketing techniques such as search engine optimization (SEO), search engine marketing (SEM), content marketing, influencer marketing, content automation, campaign marketing, data-driven marketing[6] and e-commerce marketing, social media marketing, social media optimization, direct marketing, display advertising, e–books, and optical disks and games are becoming more common in our advancing technology. In fact, digital marketing now extends to non-Internet channels that provide digital media, such as mobile phones (SMS and MMS), callback, and on-hold mobile ring tones

4. Why Digital Marketing?
Companies who sell products and services need to advertise where people hangout... Right? People used to watch TV, listen to Radio and read Newspapers. So companies used to advertise on these channels a lot.
But in 2017, we the people don't use TV, Radio and Newspapers anymore. Now, people use laptops, tablets and mobile phones!
We are sure that your usage of TV and Newspapers have come down because of social media and internet.
Traditional media is in heavy decline. And digital media is on the rise.
Companies like Jio, Airtel, Vodafone etc. have increased internet usage in India
So if companies keep spending money on old mediums, they will die. To survive, they need to start advertising on the digital and internet channels.
And that's why digital marketing is so important.
Google estimates that a total of 1 Billion Dollars will be spent on digital channels in 2017.
...That's nearly 6,900 Cr Rupees! 
And digital marketing spending is growing every year. 
Small businesses, Entrepreneurs, and Corporate will be spending this money on digital channels. And they need digital marketers to handle this spend! 
Even political parties and non-profit organizations are looking at digital marketing to spread awareness.

6. What is Search Engine Optimization (SEO)?
Search engine optimization (SEO) is the process of affecting the visibility of a website or a web page in a web search engine's unpaid results—often referred to as "natural", "organic", or "earned" results. In general, the earlier (or higher ranked on the search results page), and more frequently a site appears in the search results list, the more visitors it will receive from the search engine's users; these visitors can then be converted into customers. SEO may target different kinds of search, including image search, local search, video search, academic search, news search, and industry-specific vertical search engines.
As an Internet marketing strategy, SEO considers how search engines work, what people search for, the actual search terms or keywords typed into search engines and which search engines are preferred by their targeted audience. Optimizing a website may involve editing its content, HTML, and associated coding to both increase its relevance to specific keywords and to remove barriers to the indexing activities of search engines. Promoting a site to increase the number of backlinks, or inbound links, is another SEO tactic. By May 2015, mobile search had surpassed desktop search. Google is developing and pushing mobile search as the future in all of its products. In response, many brands are beginning to take a different approach to their internet strategies.

7. What is Search Engine Marketing (SEM)?
Search engine marketing (SEM) is a form of Internet marketing that involves the promotion of websites by increasing their visibility in search engine results pages (SERPs) primarily through paid advertising.
SEM may incorporate search engine optimization (SEO), which adjusts or rewrites website content and site architecture to achieve a higher ranking in search engine results pages to enhance pay per click (PPC) listings

8. Path of Digital Marketing

9. Most used Social Media Platforms