WordPress is a free software that you can download and use, but to use it on the web, you'll need WordPress Hosting. If you're not ready to invest in a premium web hosting service, there are free WordPress hosting services that can help you set up a functional website. 000webhost, AccuWeb, Byet, Free Hosting No Ads, Freehostia and InfinityFree are some of the most generous free WordPress hosting services in terms of storage, bandwidth and email limits. However, they don't offer the same performance and flexibility as a quality paid WordPress hosting service.
If you're looking for a free playground to try things out, Free Hosting No Ads is a good option. But if you're looking to harness the power of WordPress plugins, this isn't the best choice. InfinityFree is one of the few free WordPress hosts that allows you to create unlimited websites and also offers unlimited bandwidth, making it a good choice for high-traffic sites. Freehostia also offers generous limits when it comes to disk space and bandwidth.
However, compatibility with the outdated version of PHP means you're probably better off with a different host for any serious WordPress project. Thanks to these free web hosting services, you don't need to spend a lot of money just to launch your own WordPress website. But eventually, because your new site starts to attract real traffic, you may decide to upgrade to a premium WordPress host like SiteGround.