A fishing line is a thin synthetic fiber that serves as a connection between the fishing rod and the terminal tackle with bait. It is usually a so-called 'monofilament', meaning it is composed of a single continuous strand, most commonly made of nylon. Basic properties include its diameter, specified in millimeters, and its breaking strength in kilograms, which determines how much load the line can withstand before breaking. Another important parameter is stretch, which is the line's ability to elongate under tension. Higher stretch helps to cushion fish runs, but reduces sensitivity to bites. In addition to classic nylon lines, there are also fluorocarbon lines, which are almost invisible in water due to their refractive index. Lines are produced in various colors, from clear for minimal visibility in water to brightly colored for better angler orientation.