A node can be a means of connection.
From the Latin nodus , the term node has different uses in the fields of astronomy , physics and computer science .
For astronomy, a node is each opposite point where the orbit of a star cuts the ecliptic . We can speak of an ascending node (when the body follows the orbit from south to north) or a descending node (if it passes in the opposite direction). These nodes are diametrically opposite.
Node in physics and electronics
In the field of physics, a node is a point that remains fixed on a vibrating body . It is, therefore, the point of a standing wave that has zero amplitude at any time. For example: in a vibrating string, the nodes are usually the ends.
Another use of the node concept is found in electronics , where it is a means of connection between two or more elements of a circuit.
The concept in computing
A node, in computing, is a component that is part of a network . In other words, whether it is the Internet or the Intranet (used in closed environments, with access limited to authorized users), each server or computer constitutes a node and is connected to one or more other nodes.
Computer programming considers a node to be each element of a linked list, tree, or graph in a data structure. Each node has its own characteristics and has several fields; at least one of these must function as a reference point for another node.
The components of a network are called nodes.
Linked list and nodes
A linked list is a data structure that can be used to implement new structures (such as queues, stacks and their derivatives) and is made up of a series of nodes that store, in addition to the desired information, a link, a pointer or a reference to the node that precedes it, the one after it, or one to each. The fundamental advantage of a linked list compared to a conventional vector is that its elements do not have a rigid order or related to the one they had at the time of being stored, but rather it depends on the link that each node has, and can be modified when so desired.
Linked lists are a type of self-referencing data , since they have a connection to another element that belongs to the same type. It is worth mentioning that, although they allow the intersection and elimination of their nodes, they do not allow access to them randomly. Among the different types of linked list, there is the simple, the doubly linked, the circular and the doubly circular .
Forms of creation
There are many programming languages through which it is possible to implement a linked list; Some examples are Scheme and Lisp, which offer objects of this type, as well as methods for their convenient administration. Within the group of imperative and object-oriented languages, there are also tools that facilitate their creation.
It is interesting to note that a node can contain another list ; This practice, although very complex and unnecessary for a simple application, can be extremely useful and allow a very high level of optimization. Lisp was the first language to implement this model, but over time it became a common aspect of functional programming.
Finally, linked lists can be created dynamically (that is, at run time) or by hand, by uploading by a person, and are very common in high-volume databases .
NoDo or NO-DO, an acronym
The acronym NO-DO finally comes from Noticiario Documental and was the name of a short news program that Spanish cinemas had to show before movies.
NO-DO was in force between 1942 and 1981 . In total, more than four thousand newsreels were produced and exhibited.