Network latency, is an expression of how much time it takes for a packet of data to get from one designated point to another. It exists and varies by distance, media of data traffic runs by and on. The media includes optical fiber, copper cable, wireless electronic ware, etc. Generally, the longer distance, the more latency. That means it use more time to deliver a package of data and to receiver the response. We can try the demand of ping to test the latency between your pc and the pinged serve.

For example:
It takes 45/71 milleseconds and 274/337 milleseconds to finish the sending package and receive a response to/from amazon.com hosted at US and amazon.cn hosted at China.

C:\Users\pcadmin>ping amazon.com
Pinging amazon.com [176.32.103.205] with 32 bytes of data:
Reply from 176.32.103.205: bytes=32 time=45ms TTL=232
Reply from 176.32.103.205: bytes=32 time=71ms TTL=232
Reply from 176.32.103.205: bytes=32 time=70ms TTL=232
Reply from 176.32.103.205: bytes=32 time=62ms TTL=232

C:\Users\pcadmin>ping amazon.cn
Pinging amazon.cn [54.222.60.218] with 32 bytes of data:
Reply from 54.222.60.218: bytes=32 time=286ms TTL=225
Reply from 54.222.60.218: bytes=32 time=274ms TTL=225
Reply from 54.222.60.218: bytes=32 time=303ms TTL=225
Reply from 54.222.60.218: bytes=32 time=337ms TTL=225

Although the latency is at the level of decades of milleseconds within one country or continent, and at the level of hundreds of milleseconds between continents. It affects much the user’s experience of network-based application. Foe example, I can login the Chase APP within 2 seconds in USA. In contrast, it takes me 10 seconds to get into my Chase account when I travel to China. The difference of login speed lies in the variance of network latency between my cell phone located in USA and China and Chase APP server in USA. I can tolerate the 10 seconds of waiting for login my bank app, after all I do not use it too much every day.
However, In business area. Network latency bring much influences to business model, competitive force, especially to the operation with high reliance on time-efficient. In the book, Flash Boy, introduced the story of re-constructing a fiber between New York and Chicago. The new fiber is more straight and shorter, less nodes, decrease the network latency from 17 milleseconds to 13 milleseconds. This latency of 4 less milleseconds means faster communication between the two trade center in Chicago and New York.It creates much advantages for those high-frequency-trades who use this high-speed fiber over others.

http://5b0988e595225.cdn.sohucs.com/images/20171011/09988639262a4773835a9f62791b32ee.jpeg

https://gizmodo.com/getting-lost-down-the-rabbit-hole-of-private-infrastruc-1562782580

In wireless areas ,there is also much difference among different protocols, technologies. The standard of 5G was just formed and come to agreement and accepted by all the related associations. Just like what Nole Starosielski described in “Fixed Flow – Undersea Cables as Media Infrastructure”, the construction,investing, and maintenance of undersea cables were mixed with much impurely technical factors, such as political interference, inequality, inception, business competitiveness and chaotic, etc. These factors were also entangled inside process of forming the 5G standard. Anyway, 5G era is coming and let’s google, facebook, wechat more and faster…