What are carbon offsets?

Offsetting carbon is doing something else to compensate for the greenhouse gas emissions you either can’t or won’t reduce. For example, planting trees to compensate for the greenhouse gas emissions generated by driving a car or paying for the establishment of renewable energy somewhere in the world. Most often a third-party is paid to undertake the offset on behalf of an individual or organisation.
Common carbon offsets are tree planting and renewable energy such as wind farms.