2.3  Personal Media
The most fundamental meaning of "multimedia" is "digitally-unified media". 
In particular,  "multimedia teaching/learning materials" are "digitally-unified teaching/learning materials".   They are digital documents.
There would be many significances of digitally-unified-media.   But the followings are the most important:
- Realizing both personal and very powerful media
 - Convenient for information distribution
 
Those information expressions which were impossible to make without spending much money and labor are now reachable by a person in his private capacity, especially on a personal desktop.
For example, compared to publishing printed matters,  there are following merits in making multimedia materials as digital documents:
- One can complete the whole process by oneself.
 - Low cost and high quality
 - Agreeably spacious layout
( In the case of printed matters, "space is money".  This is not the case for digital documents. )