Parenchyma tissue is a type of simple permanent tissue that is found in plants. It is typically composed of living cells that are thin-walled, unspecialized in structure, and therefore adaptable to various functions. Parenchyma cells are non-vascular and composed of simple, living, and undifferentiated cells, which are modified to perform various functions. They are found in many places throughout plant bodies and are actively involved in photosynthesis, secretion, food storage, and other activities of plant life. Parenchyma is one of the three main types of ground, or fundamental, tissue in plants, together with sclerenchyma (dead support tissues with thick walls) and collenchyma (living support tissues with irregular walls) .

The main characteristics of parenchyma are:

• They are living permanent tissues that have the ability to divide at maturity and help in the regeneration and healing of wounds.
• The cells of parenchyma are isodiametric or polyhedral in shape. They may be polygonal, oval, round, or elongated.
• These cells are closely packed or may have small intercellular space.
• They are made up of thin cell walls made up of cellulose, hemicellulose.
• Plasmodesmata join the cells of the parenchyma tissue.
• They have several small vacuoles. In the older parenchyma, smaller vacuoles merge to become a large central vacuole, which may accumulate anthocyanin or tannins.
• The main function is to absorb water and minerals from the soil.

In animals, parenchyma is the bulk of functional substance in an organ or structure such as a tumor.