58 of the Computer Science glossary’s terms, each with the part of the syllabus where you first meet it.
The harmonic mean of precision and recall, 2 × precision × recall ÷ (precision + recall), which is high only when both are high.
The use of computer vision, usually a deep learning model, to detect a face in an image and identify or verify a person by comparing the face with stored images.
The central table of a star schema, holding one row per business event, such as a sale, with numeric measures (quantity, revenue) and a foreign key to each dimension table.
A design pattern in which a method or class creates and returns objects, choosing the concrete class from its input, so the code that asks for an object depends only on a superclass or interface and never names the concrete classes.
A design feature that makes a system move to, or stay in, a safe state when a component fails or power is lost.
Automatically switching a service to a standby server, link or device when the active one fails.
An example that is actually positive but that the model wrongly predicts as negative; a missed case.
An example that is actually negative but that the model wrongly predicts as positive; a false alarm.
The ability of a system to keep working correctly, possibly at reduced performance, when one or more of its components fail.
One measurable property of an example that is given to a machine learning model as an input, such as the number of links in an email or the floor area of a house.
Creating new features by combining or transforming existing ones, so that fewer or more informative features describe each record.
A score for each feature showing how much it contributes to a trained model's predictions.
The grid of values a convolutional layer produces by applying one kernel across its input, showing how strongly the kernel's pattern is present at each position.
Transforming the values of numerical features so that they lie on comparable scales, so that no feature dominates a model because of its units or range.
The process of choosing a subset of the existing features of a dataset that are most useful for predicting the target, and discarding the others.
Information about the output of a system, measured by sensors and returned to the controller as an input so that the output can be corrected.
A cycle in which a model's outputs influence the data later used to retrain or evaluate it, so that its errors or biases are reinforced over time.
The repeated sequence of steps by which the CPU fetches an instruction from main memory, decodes it in the control unit, and executes it, before moving on to the next instruction.
A cable that carries data as pulses of light along thin strands of glass or plastic, guided by total internal reflection.
One column of a table, holding a single property of the entity, with the same data type in every record.
A chip containing a large grid of logic blocks whose connections can be reconfigured after manufacture, so it can be programmed to act as a custom hardware circuit for a particular task and reprogrammed later.
A named collection of data held in secondary storage, which the operating system stores, finds and protects as a single unit.
A reference, returned when a file is opened, that a program uses to read from, write to and close that file.
The setting chosen when a file is opened that fixes which operations are allowed and how the existing contents are treated: read, write (replacing the contents) or append (adding to the end).
The location of a file in a file system, written as the sequence of directories leading to it followed by the file name, either from the root of the file system (absolute) or from the current working directory (relative).
The position in an open file at which the next read or write operation will start; it moves forward automatically after every read or write.
A server that stores files centrally and lets authorised users on the network open, save and share them.
The part of the operating system that organises data on secondary storage into named files and directories, records where each file's data is stored, and controls how files are created, read, changed and deleted.
The narrowing of the information a person sees online when personalisation algorithms keep showing content that matches their past behaviour and views, reducing exposure to other perspectives.
A feature selection strategy that ranks features by a statistical measure of their relationship with the target, such as correlation, calculated without training any model, and keeps the highest-ranked features.
A block attached to a try statement whose code always runs when the try statement ends, whether or not an exception occurred, typically to release resources such as open files.
Further training of a pre-trained model on a smaller, task-specific dataset, usually with a new output layer and small changes to the existing weights.
A hardware device or software program that monitors the network traffic entering and leaving a network or device and allows or blocks it according to a set of security rules.
A condition on fields of network traffic, such as direction, source or destination IP address, protocol and port, paired with an action that allows or denies the traffic that matches it.
Software stored in non-volatile memory on a hardware device that controls the device at a low level.
The rule that the item added earliest is the first to be removed.
The state of a table in which every field holds a single atomic value, there are no repeating groups, and every record is uniquely identified by a primary key.
A non-pre-emptive scheduling algorithm that runs processes in the order in which they arrive in the ready queue, each until its CPU burst is complete.
A function that gives each candidate solution in a genetic algorithm a score showing how well it solves the problem.
A text data type, written CHAR(n), that stores exactly n characters in every record, padding shorter values with spaces.
A numeric data type, written DECIMAL(p, s), that stores numbers exactly using p digits in total, s of them after the decimal point.
A Boolean variable that records whether an event has happened, set to an initial value before a loop and changed when the event occurs, so later code can test it.
Non-volatile memory with no moving parts that stores each bit as electric charge trapped in a memory cell, and that can be electrically erased and rewritten in blocks.
A database that stores all its data in a single table or file, with no links to other tables.
A design in which records in the same collection can have different fields and structures, so new attributes can be added without changing a table definition.
A data type for numbers that can have a fractional part, stored to a limited number of significant digits so that most values are approximations.
Floating-point operations per second, a measure of a processor's arithmetic speed; large values use prefixes such as tera (), peta () and exa ().
A diagram that represents an algorithm using standard symbols for each kind of step, joined by arrows that show the order in which the steps are carried out.
An arrow in a flowchart that joins two symbols and shows which step is carried out next.
To write all data waiting in an output buffer to the file on secondary storage, emptying the buffer.
A field in one table whose values must match values of the primary key in another table (or the same table), creating a link between the records.
A shape or pattern that contains smaller copies of itself at every scale, so that each part resembles the whole.
The unit of data at the network interface layer, made of a header with source and destination MAC addresses, the packet being carried, and a trailer with an error-checking value.
The number of frames (still images) shown per second of video, measured in frames per second (fps).
The end of a queue from which items are removed, and the operation that returns the item there without removing it; in an array-based queue, a pointer holds its index.
A layer of a neural network in which every neuron receives an input from every neuron in the previous layer, each connection having its own weight.
A relationship between fields in which each value of one field, or set of fields (the determinant), is always associated with exactly one value of another field, written determinant → dependent field.
A requirement that states a function or behaviour the system must provide, describing what the system does in response to particular inputs or events.