Overview
In angling, casting is the act of the angler throwing the bait and hook (or a lure) as well as other attached terminal tackles out over the water, typically by slinging a fishing line manipulated by a long, elastic fishing rod. The term itself may also be used for setting out a net when artisanal fishing.
The usual technique is to quickly flick/swing the rod forward towards the water, with the inertia of the tackles lagging and bending the rod backward (i.e. "loading" the rod), and then use the "springing" (elastic rebound) of the rod to "whip" and rapidly sling the line forward, which in turn will hurl out the hook and bait.
There are several methods anglers use to attempt to cast farther, the most prominent of which is the shifting of body weight towards the front foot in synchrony to the forward swinging of the rod. That combined with using a longer rod, stopping the rod swing at 45 degrees, and using correctly weighted and more aerodynamic terminal tackles, will help anglers cast farther.
Casting techniques
Casting techniques vary with the type and style of angling involved. Different casting techniques are also used by different anglers according to personal preferences and proficiency, and each technique is named uniquely. In the single-hand sidearm cast, the angler first points the rod towards the targeted area, and then swing it back and then quickly forward like a tennis stroke, creating a cast with a relatively flat trajectory. Drop-casting, on the other hand, is all about fast sinking, and the angler must bring the rod high before releasing the finger grip on the line and drop the cast into water with full force. The double-handed overhead cast, used more for distance, uses a kendo-like overhead swing to throw the line as far as possible.
From Wikipedia (CC BY-SA 4.0).