Braided fishing line
Braided line was one of the earliest types of fishing line, and in its modern incarnations it is still very popular in some situations because of its high knot strength, lack of stretch, and great overall power in relation to its diameter. Braids were originally made from natural fibers such as cotton and linen, but natural fiber braids (with the very rare exception of braided silk) have long since been replaced by braided or woven fibers of a man-made materials like Dacron, Spectra or micro-dyneema into a strand of line. Braided fishing lines have good resistance to abrasion, which is very important when fishing on rocky and similar terrains, where sharp objects can easily cut other fishing lines. Their actual breaking strength will commonly well exceed their pound-test rating.
Braided lines often have 1/3 to 1/4 the diameter of mono or fluorocarbon lines at a given test breaking strength.  Therefore, it is easy to fit much longer braided line on a spool than monofilament or fluorocarbon line for the same strength. This is very important for deep sea fishing, since reels don't have to be very big to accommodate long lines. Also, thin braided lines provide less resistance to sea currents.
Braided lines have no stretch, making fishing rigs very sensitive to fish bites - very important for deep sea fishing and for fish that are very gentle with the bait when feeding. Due to lack of stretch, hard hitting fish can break braided lines with very first strike. Thus it is very important to set the drag on reels on very low values.
Braided fishing lines are very flexible and easy to cast far away. Since they usually float, they are common choice for topwater rigs, too.
One drawback of braided lines is that they are highly visible in the water, and thus visible to fish. Hence, it is common to attach a fluorocarbon line at the end of the braided fishing line to serve as a leader and to reduce the high visibility of the braided fishing line.
Due to their flexibility, lack of stretch and most important, slippery surface, braided lines are hard to knot properly. There are several knots that can be used with braided lines: Palomar knot , Berkley Braid Knot, San Diego Jam Knot, Trilene knot, Albright knot etc. It is very important to tie the knots very carefully. In order to prevent knots from slipping, some fishermen add a drop of super glue.
Braided lines, particularly the newer synthetics, can be successfully used on any type of fishing reel, but are perhaps most well known as excellent lines for bait casting reels, in particular for trolling where they remain especially popular among many fishermen.