Basically, Digital marketing can be classified into 2 segments: Inbound Marketing and Outbound Marketing.

Inbound Marketing: In this technique, using social media, webinars, digital content in e-books, or e-newsletter, the number of clicks on links is increased and once can learn more about a company & its services.
Outbound Marketing: This technique includes placing of advertisements, e-mails, cold-calls or reach out potential customers through the digital mediums.

Google Adwords is a most celebrated PPC advertising system in the world. It follows PPC model. Sometimes called as Adwords only.
It is an ad service started by Google. It is for the businesses that wants to display their ads on Google. As it follows PPC model, so it allows the business owner to set an advertising budget and pay only an ad is being clicked by the user. It facilitates website owners to create advertisements that appear on Google search engine and their other properties.

Search engines are the programs that plays a very important role in finding out the specific and needed information using World Wide Web. Search engines checks for the keywords in the database and brings out the best and relevant stuff in front of the user. Some of the major search engines are:

1. Google
2. Yahoo
3. Baidu
4. Ask.com
5. DuckDuckGo
6. Bing
7. AOL
8. Excite
9. Chacha.com
10. Lycos, etc

It is designed for marketing organizations to market effectively and efficiently on multiple channels online. It is a subset of CRM. It targets the segmenting and tracking of market campaigns.

Email marketing is a marketing strategy that uses electronic mail as a medium of communication for advertising purpose. This strategy generally works for building the customer interest and increasing the current customer base by achieving their belief in you. It encourages ‘repeat business’.