28 of the Computer Science glossary’s terms, each with the part of the syllabus where you first meet it.
A logic circuit that adds two single bits, producing a sum bit (A XOR B) and a carry bit (A AND B).
A secondary storage device that records data magnetically on rapidly spinning disks (platters), using read/write heads on a moving arm.
A relationship in which an object of one class contains or holds a reference to one or more objects of another class as part of its state.
The situation in which two different keys produce the same index in a hash table.
A function that converts a key into a number used to choose its position in a hash table, always producing the same number for the same key.
A data structure that stores keys (or key–value pairs) in an array of buckets, using a hash function to calculate the bucket for each key so that it can be stored and found without searching.
The number produced by applying a hash function to a key; reduced modulo the table size, it gives the index of the key's bucket.
The clause that filters groups made by GROUP BY, keeping only the groups for which its condition is true.
The reference to the first node of a linked list, from which every traversal starts; it is null or None when the list is empty.
The number of edges on the longest path from the root node down to a leaf; a tree with only a root has height 0.
The base-16 number system, which uses sixteen digits, 0 to 9 and A to F (A = 10, B = 11, C = 12, D = 13, E = 14, F = 15), and column values that are powers of 16.
Data organised as a tree, in which each item has one parent (except the item at the top) and may have any number of children, to any depth.
Memory designed to transfer very large amounts of data per second to a GPU or other processor, using a very wide connection and stacked memory chips placed beside the processor.
A programming language whose statements are written in terms of the problem being solved rather than the instructions of a particular processor, so that one statement can stand for many machine instructions.
The use of supercomputers, very large clusters of processors connected by fast networks and run as one system, to solve problems too large for ordinary computers.
One step in a packet's journey, from one router (or host) to the next device along the route.
Increasing a system's capacity by adding more servers (nodes) and spreading the data and the workload across them.
A part of a program, such as a method or a loop, that runs so often that it accounts for a large share of the program's execution time.
HTTP sent through an encrypted connection created by Transport Layer Security (TLS), so that requests and responses cannot be read or altered in transit and the server's identity is checked.
A three-digit number in an HTTP response that reports the result of the request, with the first digit giving its class (2 for success, 3 for redirection, 4 for a client error, 5 for a server error).
A central connecting device that repeats every signal it receives out of all its other ports, without reading any addresses.
A design in which a person reviews, approves or can override an automated system's output before it takes effect, especially for decisions with serious consequences.
A topology that combines two or more basic topologies, such as star networks joined to each other through a mesh or star backbone.
A setting chosen before training that controls how a model learns or how complex it is, and that is not learned from the training data.
The process of searching for the hyperparameter values that give a model the best performance on validation data.
The application-layer protocol of the World Wide Web, in which a client sends a request for a resource and a server returns a response containing a status code and, usually, the resource.
Software that creates and runs virtual machines, sharing the physical computer's CPU, memory, storage and network between them and keeping them isolated from each other.