2G, 3G, 4G, and 5G are different generations of cellular network technologies, each offering varying levels of speed, capacity, and capabilities. Here's a brief overview of each:

• 2G (2nd Generation): 2G technology introduced digital voice communication and text messaging (SMS) to mobile phones. It provided basic data services such as email and limited internet access at slow speeds. 2G networks are mainly used for voice calls and text messaging.
  
• 3G (3rd Generation): 3G networks improved data transfer rates significantly compared to 2G. They allowed for faster internet browsing, video calling, and multimedia services. 3G networks were the first to provide broadband-like speeds on mobile devices.
  
• 4G (4th Generation): 4G networks brought substantial improvements in data speeds and overall network performance. They enabled high-definition video streaming, online gaming, and other data-intensive applications. 4G was a significant step towards the mobile internet we use today.
  
• 5G (5th Generation): 5G is the latest generation of cellular technology, designed to offer even higher data speeds, lower latency, and the ability to connect a vast number of devices simultaneously. It promises to support advanced technologies like autonomous vehicles, augmented and virtual reality, and the Internet of Things (IoT).

In New Zealand all of the cellular networks have announced plans to shut down their 3G networks to free up resources for the newer technologies. There's a summary below for each network with their plans for 3G. One NZ is the only network in New Zealand currently offering 2G services.

Spark
Spark have announced that they'll be closing down the 3G network towards the end of 2025.
See details here Spark 3G shutdown.

One NZ
One NZ have announced that they'll start to shutdown their 3G network from September 2024.
See details here One NZ 3G shutdown.

2Degrees
2Degrees have also announced they will be shutting down their 3G network towards the end of 2025.
​See 2Degrees 3G shutdown.