how do indoor plants make their food without sunlight
All the plants included indoor plants make their foods by the photosynthesis process. This process can not be performed when plants is kept in totally dark room which is not in case of indoor plants. Plants are classified into two categories on bases of light requirement.
Shade plants: This type of plants required less amount of light and they are able to perform photosynthesis process for making their food. example: Ornamental plants, Indian basil (tulsi), aloe vera etc.
Light plants: This types of plants requires high amount of light to perform photosynthesis process for making their food. If they grow in minimum light area, they will neither remain healthy nor flourish. example: mango tree, neem etc.