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Tech Terms: Blu-Ray

Blu-ray is an optical disc format such as CD and DVD. It was developed for recording and playing back high-definition (HD) video and for storing large amounts of data. While a CD can hold 700 MB of data and a basic DVD can hold 4.7 GB of data, a single Blu-ray disc can hold up to 25 GB of data. Even a double sided, dual layer DVD (which are not common) can only hold 17 GB of data. Dual-layer Blu-ray discs will be able to store 50 GB of data. That is equivalent to 4 hours of HDTV.

Blu-ray discs can hold more information than other optical media because of the blue lasers the drives use. The laser is actually blue-violet, but “Blu-ray” rolls off the tounge a little easier than “Blu-violet-ray.” The blue-violet laser has a shorter wavelength than the red lasers used for CDs and DVDs (405nm compared to 650nm). This allows the laser to focus on a smaller area, which makes it possible to cram significantly more data on a disc the same size as a CD or DVD. Proponents of the Blu-ray format say they expect Blu-ray devices to replace VCRs (thank goodness) and DVD recorders as more people make the transition to HDTV. 



Tech Terms: Node

Any system or device connected to a network is also called a node. For example, if a network connects a file server, five computers, and two printers, there are eight nodes on the network. Each device on the network has a network address, such as a MAC address, which uniquely identifies each device. This helps keep track of where data is being transferred to and from on the network.

A node can also refer to a leaf, which is a folder or file on your hard disk. In physics, a node, or nodal point, is a point of minimum displacement or where multiple waves converge, creating a net amplitude of zero.