You can replace an 8 foot fluorescent bulb with LED with a minor wiring adjustment and also use 8ft LED ballast bypass bulbs with T8 and T12 fixtures.
You do need to remove the ballast to use an LED bulb in some lights as LED lights use a built in driver instead of relying on the ballast.
Although some types of LED bulbs are designed to work with some existing ballasts and so you can install them without removing the ballast.
The ballast regulates the voltage that is needed for fluorescent bulbs to work but they are not needed for LED bulbs.
LED lights are much brighter than fluorescent bulbs and are also more energy efficient and don't have the flicker of fluorescent bulbs.
The phosphor in fluorescent lights is a white powder coating which converts the UV light or ultraviolet light into visible light.
Phosphor is responsible for nearly all of the light that is produced by the fluorescent tube and absorbs UV energy waves and releases them as visible light.
A fluorescent tube ranges from 28 watts to 40 watts for a 4 foot fluorescent tube and 96 watts for an 8 foot fluorescent tube.
The fluorescent light bulbs fit in a socket called a tombstone socket or shunted tombstone socket and require a ballast to operate.
A shunted tombstone is a light socket that has 2 electrical contacts which are internally joined to create a single path for an electrical current to pass through.
The term tombstone refers to the shape of the socket and provides a track from the ballast to the lamps pins.
Fluorescent light fixtures such as the T5 and T8 fluorescent fixtures have the shunted tombstone sockets.
Shunted sockets are light sockets that house internally connected electrical contacts.
The electrical current in a shunted socket runs on a single track from the ballast, through the socket, and then to the lamp's pins.
These types of sockets receive their voltage through a single set of wires and spread it to two contacts.
If you have shunted tombstone sockets, you will need to rewire or replace them and connect them to match the single-ended LED tube light manufacturers' wiring diagram.
If your LED tube light is double-ended, it is likely compatible with both shunted and non-shunted tombstones.