figure tree corresponding to the markup elements of web page inside the pair if you checkyou will see that this nesting property is true at all levels of the tree vocabulary and definitions vocabulary node node is fundamental part of tree it can have namewhich we call the "key node may also have additional information we call this additional information the "payload while the payload information is not central to many tree algorithmsit is often critical in applications that make use of trees edge an edge is another fundamental part of tree an edge connects two nodes to show that there is relationship between them every node (except the rootis connected by exactly one incoming edge from another node each node may have several outgoing edges root the root of the tree is the only node in the tree that has no incoming edges in figure is the root of the tree path path is an ordered list of nodes that are connected by edges for examplemammal carnivora felidae felis domestica is path children the set of nodes that have incoming edges from the same node to are said to be the children of that node in figure nodes log/spool/and ypare the children of node varparent node is the parent of all the nodes it connects to with outgoing edges in figure the node varis the parent of nodes log/spool/and yp trees and tree algorithms