next.js/examples/with-next-seo/pages/_app.js

/**
 * Using a custom _app.js with next-seo you can set default SEO
 * that will apply to every page. Full info on how the default works
 * can be found here: https://github.com/garmeeh/next-seo#default-seo-configuration
 */
import App, { Container } from 'next/app'
import React from 'react'
import NextSeo from 'next-seo'

import SEO from '../next-seo.config'

export default class MyApp extends App {
  static async getInitialProps ({ Component, ctx }) {
    let pageProps = {}
    if (Component.getInitialProps) {
      pageProps = await Component.getInitialProps(ctx)
    }

    return { pageProps }
  }

  render () {
    const { Component, pageProps } = this.props
    return (
      <Container>
        {/* Here we call NextSeo and pass our default configuration to it  */}
        <NextSeo config={SEO} />
        <Component {...pageProps} />
      </Container>
    )
  }
}