When I read the information about an SD card, I notice there is an information that is reported as 100x. What does that mean? To what is it referring?
The x rating on an SD card is a measurement of read/write speed. 1x means a speed of 1.2 Mb/s, so 100x would mean a maximum speed of 120 Mb/s (or 15 MB/s). Whether or not this refers to maximum write speed or maximum read speed is vendor-specific.