Is supply buy or sell?

Excuse me, could you please clarify something for me regarding the concept of "supply" in the context of cryptocurrency or financial markets? Specifically, when we talk about supply in relation to buying or selling, is it referring to the act of purchasing or the act of offering for sale? In other words, does an increase in supply imply that more individuals or institutions are buying into a particular asset, or is it suggesting that there are more units of that asset being offered for sale by existing holders? Understanding this distinction is crucial for accurately assessing market dynamics and making informed investment decisions.