What does this mean for you, the client? Sites are created quicker using the latest standards. Unlike CMS Websites (WordPress) that live in the cloud, the original files remain on the developer’s PC (unless he hands them over to you,) however many WordPress themes are now built using Bootstrap.
Bootstrap is not really client friendly and I use it only for my own projects and those that I control on behalf of my client. But is a very powerful platform to use when creating professional work.