What does the Base mean in 100Base-TX?

In "100Base-TX," the "Base" refers to baseband signaling, which means that the medium transmits digital signals directly without modulation onto a carrier signal. This is in contrast to broadband systems, which use multiple channels over a single medium. The "100" indicates a maximum data rate of 100 megabits per second, while "TX" specifies the use of twisted-pair cabling, typically Category 5 or higher.