What are filters in VUE.js?

In Vue js filters are used to transform the output that are going to rendered on browser.
A Vue.js filter is essentially a function that takes a value, processes it, and then returns the processed value. In the markup it is denoted by a single pipe (|) and can be followed by one or more arguments:

<element directive="expression | filterId [args...]"></element>

In Vue 2.0, there are no built-in filters are availables, however you are free to create your own filters.