Latte art or coffee art refers to designs created on the tops of espresso based drinks by a barista. These designs are usually created in one of two ways and sometimes using a combination of both.
The first method is by manipulating the flow of milk from a jug into the espresso (known as free pour latte art). Popular free pour designs include rosettas, leaves and hearts. The second is by drawing designs with an implement (known as etching), using stencils, powders and milk foam. Latte art is most commonly seen on a latte because of a latte's ideal ratio of milk to foam, although it can also be part of the presentation of a cappuccino, a caffe mocha or even an espresso macchiato. As the popularity of premium espresso-based drinks has risen, the craft of garnishing through latte art has as well.
Image Source: Coffee Geek
With the rise in popularity of latte art and artistic presentation in the cup, competitions have emerged all around the world to enable practitioners (baristas) to show off their skills.
In latte art competitions and in barista discussions, practitioners of latte art are frequently encouraged to first and foremost be attentive to the quality of the espresso and the steamed milk before consideration is given to how the drink should be completed with eye-catching art.
Information Source: Wikipedia