The phrase "voluntary contributions" refers to actions or donations that are made freely and without any obligation. In other words, it is something that an individual chooses to do on their own accord, with no external pressure or force. This can include financial donations, time spent volunteering, or resources given willingly for the benefit of others. The phrase highlights the idea that these actions are not driven by necessity or coercion but rather come from a place of generosity and goodwill.