The abbreviation gTLD stands for generic top-level domain. gTLDs include all top-level domains that have no country-specific reference. The best-known gTLDs include .com, .net and .org. The gTLDs are assigned by the Internet Corporation for Assigned Names and Numbers LD (ICANN).
The so-called New Top-Level Domains (New gTLDs, often abbreviated as nTLD for simplicity) are a subgroup of the gTLDs.