Carrier Sense Multiple Access (CSMA) as i understand it is a MAC protocol in which a host waits for zero traffic before transmitting over network media.

Carrier Sense Multiple Access With Collision Detection (CSMA/CD) is the same as CSMA except when transmitting data the host detects another signal while transmitting a frame, stops transmitting that frame, transmits a jam signal, and then waits for a random time interval or a "back-off" delay before trying to send that frame again.

Wavelength Division Multiplexing (WDM) uses multiple lasers to transmit light via fiber optics. Every pulse stays within its assigned color band. That pulse modulates in intensity according to the data being transmitted.

Can anyone elaborate for me or tell me something about these I should know? Get I understand these terms correctly?

Carrier Sense Multiple Access

Used in bus networks, where multiple hosts are on the same electrical bus; think classical ethernet with a bunch of hosts setting on a long coax cable, or cat-5 ethernet with a hub. Two commonly used variations:

CSMA/CD
Ethernet is the best example, and works just like you described it. It's characterized by the fact that there's no before-hand synchronization between hosts, anyone can transmit at anytime ... if a collision occurs, the hosts work it out among themselves when it happens.

CSMA/CA ( Collision Avoidance)
Think ring networks, or any token passing network in general. A token is passed around to each hos on the bus. They can only transmit when they hold the token, hence there are (should not be in a valid config) any collisions. But the hosts have to stay synchronized via the token, they can't transmit whenever they want. If host A wants to transmit, it has to wait for the token to be passed around, even if nobody else wants to transmit.


WDM/DWDM ( Dense-WDM)
I'd say the primary difference between this one and the previous two are that it's a point-to-point topology, rather than a multipoint technology. You'll see it more on WAN links probably for this reason.

As Cisco has products / modules that support all of these technologies, you might want to check out the documentation on their website.