What are Nuxt.js plugins?

Plugins in Nuxt.js are files stored in the plugins/ directory that run before the Vue application is mounted. They are used to integrate third-party libraries, provide global utilities, register global Vue components, or extend the Nuxt application context. Plugins can be run only on the client (suffix .client.ts), only on the server (.server.ts), or on both. A plugin exports a default function using defineNuxtPlugin(). The provide helper inside plugins makes utilities available globally via useNuxtApp().$myHelper.