A domain with a name containing one "dot": for example, "ipr-helpdesk.org", "google.com" or "lemonde.fr". This can be distinguished from a third-level domain, containing two dots (such as "qmul.ac.uk"), a fourth-level domain, containing three dots (such as "seda.demon.co.uk"), etc.(ES:Dominio de segundo nivel, IT:Dominio di secondo livello, FR:Domaine de second niveau)
The domain name system is designed as a hierarchy. The root is the highest level of the hierarchy, followed by the top level domain, then followed by the second-level domain. For example, for the domain "espn.com", "espn" is the second-level domain, "com" is the top level domain, and the "." is the root.
a child of a first-level domain, and so on
a child of the first-level domain
In the domain name system (DNS), the next-highest level of the hierarchy underneath the top-level domain. Located immediately to the left of the dot (" . "), the second-level domain is the "readable" part of the domain name. The second-level domain often refers to the organization or entity associated with the IP address. For example, in: yourdomain.com, "yourdomain" is a second-level domain.
A domain in the Domain Name System (DNS) that is immediately under a top--level domain.
In the Domain Name System, the next lower level of the hierarchy underneath the top level domains. In a domain name, that portion of the domain name that appears immediately to the left of the top-level domain. For example, the eurISP in eurISP.co.uk Second-Level Domains are the focus of domain speculators and have been the root of a good portion of internet name disputes on the internet. It's important that your second-level domain does not infringe upon the registered trademark of another entity.
The portion of the domain name before the name.extension. For example, www is a very common second level domain of most domain names.
A second-level domain (SLD) is the part of a (URL) that identifies the specific administative owner associated with an (IP address). The SLD includes the primary domain name for example UNT is the SLD and edu is the primary in unt.edu.
In the Domain Name System (DNS), second-level domains are the next lower level of the hierarchy underneath the top-level domains. In a domain name, it is that portion of the domain name that appears immediately to the left of the top-level domain (for example, the "neustar" in "neustar.cn"). Second-level domain names are often descriptive and have come to be used increasingly to represent businesses and other commercial concerns on the Internet.
In the Domain Name System (DNS) hierarchy, a second-level domain (SLD) is a domain that is directly below a top-level domain (TLD). For example, in en.wikipedia.org, wikipedia is the second-level domain of the .org TLD.