There are two tupes of line primarily used for spooling onto reels, and other lines for use as leaders.
Braided Line - Braided line is rapidly becoming the new standard line for spooling reels with. Braided line has a significant strength to diameter ratio as compared to monofilament; typically when comparing lines with equal diameter, the braided line will be twice as strong as the Monofilament which also means that it is able to be cast farther. Braided line also has the advantage of being more resistant to saltwater and sunlight
Braided line does have a couple of disadvantages; Braided line tends to be less abrasion resistance, if you rub across the reef, or barnacles on a dock or something similar, it is more likely to break. Also, as braided line has less stretch, it requires a softer hand, and a lighter setting on the drag to stop it from being broken on sudden snatches.
Monofilament - Monofilament line is the most popular line used to spool reels with. Monofilament is thin, strong, and abrasion resistant. Monofilament also offers goot water resistance and knot strength.
Monofilaments biggest disadvantage is sun resistance. It breaks down pretty fast in the sun, and should be replaced as often as every six months to a year.
Fluorocarbon - Flourocarbon line is a newer material used to make fishing line with. Fluorocarbon line isn't typically used to spool a reel with, but most often used for leader material to tie to your spooled line.
Fluorocarbon line offers low light refraction, and is nearly invisible in the water. It is also very abrasion resistant, and sinks fast, again making it a good leader material. Like Monofilament line, Fluorocarbon line is prone to deterioration.
Wire - Wire is not used to spool reels with, but is used as a leader material when targeting toothy fish such as Mackerel and Wahoo. There is single strand and multi strand wire. Single strand is a tougher to work with, and less flexible than multi strand wire, but it's advantage is being stronger per unit diameter.