A 4th-generation (4G) wireless cellular mobile radio technology. It is the main radio technology that powers mobile phone networks. It replaced 3G technologies (including WCDMA and CDMA) starting around 2012, and is being gradually phased out in favor of 5G (NR) technology starting in 2020.
Its primary feature for users (compared to 3G technologies) is faster data, although it also improves the efficiency and capacity of wireless networks.
LTE is considered a 4G technology both because it is faster than 3G, and because it uses an "all-IP" architecture where everything (including voice) is handled as data, similar to the Internet.
The technical standard that defines LTE is called 3GPP Release 8 (or greater).
The first version of LTE to be widely deployed was LTE Category 3. It supports download data rates of up to 100 Mbps.
Newer versions include Category 4, 6, 9, 16, etc., which add new technologies such as Carrier Aggregation to boost data speeds to 150 Mbps and much higher. Higher category numbers generally correlate to faster data speeds. These newer iterations of LTE include other new technologies to make networks more efficient and robust, as well as support for denser networks to cover denser populations in urban areas.
See: Carrier Aggregation