Portable means easy to carry round,
Optical means uses light to make it work.
So optical media could be portable.
Optical disk
Linux has drivers built in already for portable media. Many times with Windows, you have to download drivers from 3rd party sources.
Optical Disk
The angle of incidence.The difference in the optical densities of the media.
The CD and the DVD.
Optical disc
Portable media player was created in 2002.
The flash media does not last as long as the optical media. Flash media is about the moment and will not be supported for as long.
optical
My understanding is that an SD card is an SD card, no matter what the use is. The difference is what data is stored on it. (eg. Photos or music)
One example of a portable media player is an ipod.
not much media is moves and video