I read this passage from my reference book. There is a sentence being bold below :
The standard SSI and MSI parts that have served as “bricks and mortar” in the building of digital systems for over 40 years are now obsolete and becoming less available. Many of the techniques that have been taught over that time have focused on optimizing circuits that are built from these outmoded devices. The topics that are uniquely suited to applying the old technology but do not contribute to an understanding of the new technology are being de-emphasized. From an educational standpoint, however, these small ICs do offer a way to study simple digital circuits, and the wiring of circuits using breadboards is a valuable pedagogic exercise. They help to solidify concepts such as binary inputs and outputs, physical device operation, and practical limitations, using a very simple platform. Consequently, we have chosen to continue to introduce the conceptual descriptions of digital circuits and to offer examples using conventional standard logic parts
What does "solidify" meaning in this sentence ?