Title-tag

Title tags are important for SEO, or search engine optimization. The text in a web page’s title tag is used by search engines as the link to the page in search results

The title tag is also visible at the top of the web browser and web browser tabs when you’re on a web page, so it helps orient people and make it easier for them to find your site again if they have lots of tabs or windows open.

Additionally, the title tag is often used when people share a link to a web page on a social site like Facebook.

TLD

A top-level domain (TLD) is one of the domains at the highest level in the hierarchical Domain Name System of the Internet. The top-level domain names are installed in the root zone of the name space. For all domains in lower levels, it is the last part of the domain name, that is, the last label of a fully qualified domain name. For example, in the domain name www.example.com, the top-level domain is com. Responsibility for management of most top-level domains is delegated to specific organizations by the Internet Corporation for Assigned Names and Numbers (ICANN), which operates the Internet Assigned Numbers Authority (IANA), and is in charge of maintaining the DNS root zone.