Fungi exhibit certain characteristics, one of which is that they are achlorophyllous, that is they do not have chlorophyll , which is necessary for photosynthesis. Thus due to this, fungi cannot perform photosynthesis and therefore cannot make their own food but rely on readymade food matter.
They mostly feed on dead organic matter the process of absorption. Some fungi release enzymes that help break down dead organics matter into chemicals that the fungi can absorb as food. Other fungi obtain food directly from living beings, which means they are parasitic.