A tea infuser, also called a teaball (tea ball) or tea maker, and sometimes referred to as a tea egg, is a device essentially used for steeping tea. Loose tea leaves are placed in the tool and it is then immersed in hot water, usually in a cup. Essentially, the infuser is a small mesh that allows easy steeping. Traditionally, tea infusers were made from metal alone and there was one standard design. In the modern times, however, infusers are made from a range of materials and the designs also vary. 
The most basic and traditional tea infuser is a mesh ball. Loose tea is placed in the mesh ‘ball’ that opens in half and the device is then inserted in hot water. Once the tea has infused, the tea ball is removed. The infused leaves cannot be reused and have to be discarded. The device is popular for its ease of use. Some mesh ball infusers come with measuring spoon conveniently attached at the other end. This just makes the brewing process a little easier. 
The next ‘level up’ for tea infusers are floaters that bob on the water level and house a mesh infuser under the water to steep your tea. They come in a variety of cute designs like rubber ducks or water lilies to dress up your cup.
Stick infusers are the newest products on the market and they take up less space and move away from the previous thought that the infuser has to be fully submerged. The infuser sticks are easier to store and clean plus many tea connoisseurs claim that they steep faster with a stronger taste. 
Acting as a filter, today’s infuser can float atop the hot water or be immersed deeply in the cup or pot. With spring-action handles or built-in scoops, modern infusers have made steeping almost effortless. The durable and colorful silicone infusers on the market today were preceded—and are still accompanied by—the metal and mesh tea-ball infusers.
Regardless of the design, some general rules apply to using either an infuser or a tea ball. Fill the device only halfway with tea leaves to allow for movement and expansion. This will release optimal flavor. Base your choice of infuser on the size of the tea leaves—the smaller the leaves, or pieces of leaves, the smaller the holes in the infuser.
High-tech or low-tech, silicone or sterling silver, the types of infusers are as varied as the cups of tea they create. Fanciful tea balls, fine strainers, and contemporary infusers illustrate the evolution of steeping, as well as the range of devices that have made infusing a way to customize the beverage and maximize the experience.