Today a big chunk of the web traffic is made by mobile devices. Each device can have different screen sizes (usually with a width of 320 pixels), but the aim is to create a web site that can work reasonably well with all these kind of different small devices.
All Drupal functionalities such as registration form must be built in a way that user can use the form for these small devices, users can still login from them to check their account, check, edit or make new orders, find new products. All the Drupal functionalities should be active also for these small devices so that there are no limitations as the screen resolution became smaller.
Drupal Themes can be created from existing responsive themes such as Omega and then customise it. Theming is a fantastic Drupal feature to implement any kind of design in terms of responsive structure such as setting up regions with a 12 grids responsive layout, very good for mobile.
Multilanguage - i18n Drupal module supports translation for nodes, taxonomies, url alias, meta tags, menus and blocks. Set up the site default languages and then for each piece of content add the relative translation.
How to develop a Custom Service in Drupal 8
Great expertise in web development, Agile environment, JIRA and project management, Github and SVN. Mostly specialised in Drupal Backend Development with also strong front-end skills in JavaScript, JSON, JQuery, Ajax, HTML/CSS, XML/XSLT.