Speed is a measure of how fast something is moving. It's calculated by dividing the distance traveled by the time taken to travel that distance.

Here's a more formal definition:

Speed is the rate of change of position of an object in a given direction.

Here are some important points to consider:

* Speed is a scalar quantity: This means it only has magnitude (how fast something is moving), not direction.

* Velocity is a vector quantity: This means it has both magnitude and direction (how fast something is moving and where it's going).

* Units of speed: Speed is typically measured in units like meters per second (m/s), kilometers per hour (km/h), or miles per hour (mph).

Let me know if you'd like more details or examples!