What is WordPress Multisite (WPMU)? WordPress multisite network is a collection of sites which share same
WordPress installation and can also share plugins and themes. Although they do have separate directories for media uploads, and have separate tables in the database.
What is important in WPMU? Structure plays most important role in deployment of a WPMU installation. Either, you have to choose a sub-directory or sub-domain install. Note: If your installation is 30 day+ old, you have to stick with sub-domain install.
What is domain mapping? It is masking for your domain to make & feel like a different or independent website. If you want to map multiple domain from same installation, then, structure is not necessary at all. Note: Additional domain need proper nameservers.
What I need Your Web-hosting and WordPress dashboard log in credentials.
Total WPMU Package If you do not have WordPress installation. Then, I offer complete WPMU setup along with personal favorite plugins set.