There are four types of junctions in a cell. They encircle the cells, join two cells together at a specific spot, or form a tunnel connecting the cytoplasm of the adjacent cell.
Plasmodesmata
Plasmodesmata is a small thread of cytoplasm that goes through the cell walls of adjacent cells and allows communication between them.
Tight Junctions
Tight junctions form the closest contact between adjacent cells known to mankind. It's found in the apical region around the cell's circumference.
Desmosomes
Desmosome connects the plasma membrane to intermediate filaments in the cytoplasm. It is very important in stratified epithelium.
Gap Junctions
Gap junctions are intercellular channels in the plasma membrane of adjacent cells. This allows some molecules to travel from one cell to another.