Um responsive site is one that automatically adapts to the device the user is using to access the content, be it a smartphone, laptop, computer, or tablet. Regardless of the screen size, the page will present a light, pleasant, and linear layout, always allowing for the best viewing experience on any type of device.
One of the reasons to be concerned about responsiveness it is precisely the fact that smartphones, which come in different sizes and have different operating systems, have become the main means of accessing the internet in Brazil, according to data from the Information and Communication Technologies (ICT) Supplement of the National Household Sample Survey (Pnad) 2015, the most recent survey on the subject released by the Brazilian Institute of Geography and Statistics (IBGE).

According to the survey, in 92,1% of Brazilian homes, internet access is via cell phone, compared to 70,1% via computer. Since 2015, everything suggests that this number has only increased – which makes this an essential time to consider the development of a website that suits the user's browsing preferences.
Relevance that generates audience

Since April 2015, Google has given more relevance in searches to sites that offer a good experience for different devices, that is: it started to consider responsiveness when positioning pages in the results ranking.
Therefore, a website “Mobile First” (which values browsing via mobile devices) can gain prominence more easily and, therefore, receive more access by simply adapting to the screens used by users.
Um big benefit no additional costs if the website is already created prioritizing the optimization of the internet user experience.
The era of responsive websites

With smartphones becoming increasingly indispensable in people's daily lives, you only need to look around to see proof of why this is the age of responsive websites: people with their eyes fixed on the screen.
And those who are focused on websites and mobile apps tend to continue doing so if the layout allows for a complete experience – without the need to adjust the page zoom to, for example, be able to read.
According to Google Developers, using responsive web design also reduces the risk of errors that often affect websites created for mobile devices, making this method the best for all environments: from PCs to smartphones. Furthermore, Google PageSpeed Developers also highlights that this development method also makes full page loading faster on mobile devices.
Another point worth considering is that using this type of page helps reduce the bounce rate, which is when a user accesses just one page of the site and leaves without clicking on anything. To Google's algorithm, this behavior can end up signaling that the content is not relevant – which leads to a loss in search rankings.
Therefore, focusing on creating a responsive website helps build user loyalty. If the page isn't optimized, users will spend less and less time there, leaving before any interaction, and eventually abandoning it altogether—after all, 3G and 4G aren't cheap in Brazil, but that's another discussion...
Therefore, when considering all the points, it is easy to conclude that using a responsive site é benefit for everyone: for those who offer a service or product online and for users who can easily find what they are looking for – and have immediate and effective access.