Laboratory education plays a vital role in the education of engineers. Beyond concepts and principles, laboratories help students develop essential engineering skills such as problemsolving, designing, and troubleshooting. However, the use of laboratories in engineering education may be limited by a series of factors, including the cost of equipment, time, and infrastructure. To reduce the consequences of such limitations, educators are constantly looking for emerging technologies that make the lab more inclusive, creative, and effective. Among these technologies, virtual laboratories are becoming very popular in engineering education. This paper presents a conceptual and practical framework for developing virtual labs for engineering education. The framework combines a classical backward design approach with the concepts of virtual equipment and digital twins to create virtual versions of different hands-on experiments. In these virtual experiments, students can reproduce all the hands-on practices virtually and learn concepts, procedures, and attitudes toward experimentation. The authors will discuss the theoretical foundations of the framework and present examples of virtual labs already developed for mechanical, electrical, civil, and chemical engineering education. In addition, the authors will discuss the main concerns and difficulties in creating a virtual labs web platform used by more than 1,000,000 students.