Examine the structure of this sending domain: send.brand.com. Which part of this sending domain is the subdomain?

To understand the anatomy of a domain, you have to look at it from right to left. Each section separated by a dot represents a different level of the hierarchy. Top-Level Domain (TLD): This is the extension at the very end, such as .com, .org, or .net. Root Domain (or Second-Level Domain): This is the main name of your brand plus the TLD (e.g., brand.com). This is what you usually purchase from a registrar like GoDaddy or Namecheap. Subdomain: This is the prefix added to the beginning of the root domain (e.g., send). It acts as a "branch" or a specific folder of your main domain used for a specific purpose—in this case, for sending emails.