Existing sites can be migrated to a Joomla in different ways: at the database level, manually copy + paste and automated cutting and pasting.
The choice depends on the availability of a database and the number of items that need to be transferred. Since 2005 db8 supports organizations with migrating from other systems to Joomla.
Migration at the database level
If the current site is built with a CMS and the content of the website is retrieved from a database, the contents of the website can best be migrated using database queries and be converted to a database structure that can be used by Joomla CMS.
Manually copy and paste
For small websites with up to 15 pages is the easiest way to transfer the site to Joomla by simply copying the text from the browser and put the items in the new Joomla site.
Automated cutting and pasting
For larger websites with more than 15 pages, it may be faster to write a script that indexes the content of the website, saves it into a database that can be used by Joomla CMS.