20 of the Computer Science glossary’s terms, each with the part of the syllabus where you first meet it.
A diagram in the Unified Modeling Language that shows classes as boxes listing their attributes and methods, and the relationships between the classes as lines.
The result of a model being too simple to capture the underlying pattern in the data, so that it performs poorly on both the training data and new data.
A universal character set that gives every character of the world's writing systems, together with symbols and emoji, its own number, called a code point.
A design in which the CPU, GPU and other processors on a chip share a single pool of RAM, so that data does not have to be copied between separate memories.
A text address that identifies a resource on the web and how to retrieve it, made up of the protocol, the domain name of the server, and the path to the resource.
The set of all elements that are in either of two sets, or in both, with each element included once; written .
Testing one small part of a program, usually a single subprogram, on its own, by calling it with chosen inputs and comparing the results with the expected outputs.
A logic gate from which any other logic gate, and therefore any logic circuit, can be built; NAND and NOR are the two universal gates.
The state of data that has not been normalised, in which a table may contain repeating groups, fields holding several values, or no primary key.
Software that is missing an available security update and therefore still contains a vulnerability that is publicly known and may already be exploited.
A whole number stored in binary without a sign, so it can only be zero or positive; with bits it can hold values from 0 to .
Data with no predefined model of fields and types, whose meaning cannot be split into the columns of a table.
A type of machine learning in which a model is trained on unlabelled data and finds structure in it, such as groups of similar examples or items that occur together, without being given correct outputs.
The phase of recursion after the base case is reached, in which each call returns its result to the call below it and its stack frame is popped, until the original call returns.
A view through which rows can be inserted, updated or deleted, with the changes passed on to its base table; a view that does not allow this is read-only.
A fault in a poorly designed table where one fact is stored in several records, so changing it means updating every copy, and missing one leaves the data inconsistent.
A small, portable storage device containing flash memory and a controller, which plugs into a USB port.
A connectionless transport protocol that sends each message as an independent unit, with no handshake, no acknowledgements, no retransmission and no guarantee of order.
A short description of a feature from the point of view of the person who will use it, usually in the form "As a [user], I want [action] so that [benefit]".
A variable-length encoding of Unicode that stores each code point in one, two, three or four bytes, using a single byte for the 128 ASCII characters.