Qt Quick is Qt's declarative UI design system, using the Qt Modeling Language (QML) to define custom user interfaces. Originally developed for use in mobile applications, it offers dynamic graphical elements and fluid transitions and effects allowing you to replicate the kinds of UIs you find on mobile devices. Qt Quick is supported on all desktop platforms too and is a great choice for building desktop widgets or other interactive tools. Qt Quick is also a great choice for developing UIs for hardware and microcontrollers with PyQt5.