Nuget Build, when it PackageName.Targets and PackageName.props consumed?

Given, a package file called example:

<?xml version="1.0" encoding="utf-8"?><package><metadata><id>example</id><version>$version$</version><title>$title$</title><authors>$author$</authors><requireLicenseAcceptance>false</requireLicenseAcceptance><description>$description$</description><copyright>$copyright$</copyright></metadata><files><file src="example.targets" target="build" /><file src="example.props" target="build" /></files></package>

When is example.targets and example.props consumed?

Originally I thought it was only during the build process for the project that is using the Nuget package.

But it seems to use props files on installation?

I'm using old-style packages.config in my consuming projects.

Anyone point me to details on this or advise. Thankyou.