WordPress is the most popular platform for blogs.  It started as a simple way to host a linear collection of posts, but over time has grown into a full content management system.  A robust collection of plugins and themes makes it easy to run an entire website with WordPress alone, without having to rely on other platforms.

It is possible to host a WordPress blog directly on wordpress.com, but these days most people prefer to download the stand-alone version and install it on their own hosting.  It’s available for free and without ads.