Simply DVI in its fullest configuration has DVI-Digital (very similar to HDMI), and basically VGA, on one largish plug. The VGA video and DVI-Digital are on different pins of the connector, except share some control leads. A DVI to VGA adapter or cable connects just the VGA and control pins, a DVI to HDMI adapter the digital video and control pins to the HDMI plug. So there, you cannot convert HDMI to VGA using DVI plug adapters as an intermediary because the digital and analog video are on different pins, the signals still strictly separate. As for the descriptions: VGA is analog computer graphics. It has discrete R/G/B video leads with separate sync pulses, and DDI lines to tell the computer display capabilities. DVI-D is bascally the same, except is digital, and uses differential signalling, and as well has a signal clock. DVI has a dual link version that has an extra set of RGB signal lines, for extra color depth or resolution. As said above, DVI-I is a combo connector with DVI-D and VGA. HDMI is basically DVI-D only on a smaller connector, with differential SPDIF audio added, and CEC. RCA and BNC are simply types of single circuit plugs. RCA is used for consumer A/V, BNC for commercial video and RF. Composite is a video signal that has a luma (sum of R, G, and B video, called Y), and chroma. (red-Y and blue-Y modulated on a carrier). S-video is the same video signal, but have the Y and C signals on separate lines. That allows more bandwidth and no cross interference for each, meaning an improved picture. It is still hobbled by the bandwidth and frequencies of the carrier. Component takes that one step further, having each color difference signal have its own line. That improves bandwith and allows high resolution. For analog consumer A/V, they all use RCA plugs for the video and stereo audio, except S-video, which typically uses a 4 pin mini-din for picture, RCA for sound. The standard for Toslink is a squarish plug, but some equipment use a likeness of a 3.5mm plug. To add is digital audio. On consumer equipment, that uses a standard called SPDIF, and uses an RCA plug/cord the same as video. Optical audio is called TOSLINK, which basically is SPDIF with a light emitter and receiver, which connect with a fiber optic cable.