A Content Management System is a pre-built and constantly updated core structure that can be installed easily, then modified and themed to suit the desired requirements of the blog.
There are many extensions and plugins to these that provide a certain specialized function or facility, saving hours of coding and development costs.These can be installed and uninstalled without adversely affecting the core of the system. Many plugins, extensions and themes are available free of charge.
It takes another level of skill to determine and choose the right theme and plugin to implement and achieve the individual blog’s best outcome. Usually is a mix of free and paid plugins.