Yes they are. Another way of describing our websites is as being responsive depending on what device they are being displayed on or even which way they are being held.
Approximately 2 years ago we started making all of our websites responsive. Mainly this is down to Rockettheme - the company who make templates, modules etc. for Joomla and Magento.
They are the experts in what they do and their templates have proven to be very flexible and customisable allied with sophisticated CSS design makes their products and our websites hard to beat.
For some years now we have been using the Magento eCommerce Platform to make our webstores and have found them to work very well in mobiles and tablets too.
A common question now "is my website mobile-friendly and will it work on tablets?" - Try the Google Mobile-Friendly Test to see if your current website is mobile-friendly?