Communication involves the transfer and understanding of meaning between individuals. Poor communication is often cited as a major cause of conflicts. Communication can flow vertically up and down an organizational hierarchy or laterally between peers. Upward communication provides feedback and ideas for improvement to managers, while downward communication relays goals and policies. Lateral communication occurs between peers. Both formal and informal networks exist, with the informal grapevine often spreading rumors and being perceived as more reliable than official communications. Nonverbal communication also conveys important messages through body language and expressions.