You don’t necessarily need to buy a domain name to build an online presence. You can publish your content on third-party websites, but keep in mind that they will likely keep the ownership of your work, sometimes restricting you from moving it or using it on other websites. Buying a domain name gives you full ownership of your website, your content, and most importantly, your branding. No one else will be able to use the same domain name, reserving it for your use only as long as it’s registered to your name. Not to mention that owning a domain name will make you seem a lot more professional and serious about what you do.