The Need of Responsive Websites
Today, we have got very advanced devices such as notebooks, Smartphones, tablets, etc. People prefer different devices to view any website or any information on the internet. But the website we design is of the size of the device (for e.g. desktop) we work on. So, people viewing your website on different devices with different screen sizes may find it difficult as the default size of the website is different for each device. Hence, there is a need for Responsive websites.
Responsive websites are those that are flexible and can adapt the size of the device where the website is viewed on and makes it look attractive for the user. If someone viewed your website on a Smartphone, it would be shown the same size as someone else who is using a desktop to view your website. With this responsive website, there is no need of zooming in or out to view the content of the website. You won’t even have a trouble of moving the page left or right to view the whole content. Every page is adjusted accordingly.
A non-responsive website looks as follows on different devices:

This doesn’t make a site flexible to the user. This is how a responsive site looks on different devices:

There are some more reasons which make responsive websites more and more happening. The benefits of Responsive web design are:
Smarter, better, faster user experience: Irrespective of the platform they view your website on, users enjoy features such as faster loading of the website, best-upgraded websites and flexible view of websites. This is what makes a user happy, and that is what makes a business happy. The more it is easy to use and understand, the more clients/viewers your website can get.
Cost Effective: Though Responsive websites take a little longer time to design, they survive for longer time and support. Maintenance and upgrades have to be done only in a single place which saves money and time.
Future proofing: Responsive sites work well on the multitude of already existing devices in the market. It might take some time to come.
Improve conversion rates: These sites provide the best experience to the users no matter what platform they view your site on, and this increases the engagement of users with you than going anywhere else. This makes you receive more and more projects.
SEO was optimized: Though SEO is an important aspect for every blog/website, it is hard for managing SEO to separate tablets, mobile and desktop sites which don’t produce great results. A responsive approach is recommended by Google to overcome these problems and gives a consolidated view of your results with more focus.
There are many methods being implemented and used for responsive sites for almost all websites that are being designed nowadays. The most common expectation of a user from a web designer is the Responsive site.
We can make our website responsive using HTML, CSS, jQuery through some piece of code, but inserting the libraries of bootstrap makes your work much easier, i.e., your website becomes automatically responsive if it is built using Bootstrap. You can learn how to use Bootstrap in one of these online courses
You can learn how to create your responsive website here.