Activation (noun)

1. The process of making something active or operational.
2. The process of causing a chemical reaction or a physical change by adding energy.
3. The process of enabling a computer program or a device by entering a code or making a configuration change.

Origin:

From latin activatio, from activare ("to make active"), from actus ("a doing, a driving") + -vare ("to make") -ive.

Examples:

1. The activation of the alarm system was done by pressing the button.
2. The activation of the catalyst led to a faster reaction.
3. The activation of the software required a valid license key.
4. The activation of the nuclear reactor was a complex process.
5. The activation of the device was done by connecting it to the internet.