Responsive Web Design
Responsive Web design is the approach that suggests that design and development should respond to the user’s behavior and environment based on screen size, platform and orientation. The practice consists of a mix of flexible grids and layouts, images and an intelligent use of CSS media queries.
As the user switches from a desktop or laptop to and iPhone or iPad, the website should automatically switch to accommodate for resolution, image size and scripting abilities. In other words, the website should have the technology to automatically respond to the user’s preferences. This would eliminate the need for a different design and development phase for each new gadget on the market.
SEO Mobile Friendly
Google is constantly evolving, and so we all need to evolve with them. Google recently announced their biggest adjustment: ranking mobile-friendly websites. Google will now rank your site differently if it isn't "mobile friendly".
From 2015 Google Search is considering mobile-friendliness as a ranking signal. This change is having a significant impact in Google Search results. Users will find it easier to get relevant, high quality search results optimized for their devices. To help you make sure your website is ready for this search change.
Mobile Technology is Changing the User's Web Surfing Habits
Individuals who surf the Internet through their smartphones or tablets are often much less likely trying to decipher a difficult to understand marketing message than someone on a PC. If something isn't immediately interesting or relevant to a mobile device user, they’re likely to switch to another site right away.