What is latency?

Latency is the amount of time it takes for data to travel from one point to another in a system. Think of it as the “delay” you notice between pressing a button (like sending a message) and seeing the result (the message appearing on the screen). It’s usually measured in milliseconds (ms).

Let's break it down

  • Propagation delay - the time a signal needs to move through a medium (like a fiber‑optic cable).
  • Transmission delay - how long it takes to push all the bits of a message onto the wire.
  • Processing delay - the time routers or servers spend looking at the data and deciding where to send it.
  • Queuing delay - waiting time when data sits in a buffer because the network is busy. All these pieces add up to the total latency you experience.

Why does it matter?

Low latency makes interactions feel instant, which is crucial for:

  • Online gaming (no lag, smoother play)
  • Video calls (natural conversation flow)
  • Real‑time financial trading (tiny delays can cost money)
  • Cloud applications (quick response times keep users happy) High latency can cause frustration, errors, or even safety issues in time‑critical systems.

Where is it used?

  • Internet browsing - loading web pages and streaming videos.
  • Mobile networks - 4G/5G performance for apps and streaming.
  • Cloud services - accessing data or running programs hosted elsewhere.
  • IoT devices - sensors and actuators that need fast feedback.
  • Gaming consoles and PCs - multiplayer and cloud gaming platforms.

Good things about it

  • When latency is low, users enjoy a seamless, responsive experience.
  • Enables real‑time technologies like VR, AR, and autonomous vehicles.
  • Improves efficiency in business processes that rely on quick data exchange.
  • Drives innovation in edge computing, where processing is moved closer to the user to cut latency.

Not-so-good things

  • High latency can make apps feel sluggish, leading to user abandonment.
  • It can cause synchronization problems in multiplayer games or collaborative tools.
  • Reducing latency often requires expensive infrastructure (e.g., more servers, better routing, fiber links).
  • In some cases, network congestion or long physical distances make it hard to achieve low latency without major upgrades.