SEO (search engine optimization) or ASO( App search optimization). web and app nowadays worth with same ways and both need each other.
like if you have an only app or not website than you will not get a good ranked in-app store or if you have the only web or not app than your web never gets top position in google due to missing the app.
There is some difference between SEO or ASO:
How Rank SEO and ASO?
Its very simple just buy SEO or ASO Service provider . and Follow the google rule’s.. also read what is changing in google alogthrium
What important point will in mind?