Sequential

Sequential describes things arranged in order or related to following a sequence of events. The term comes from Latin sequi, to follow.

In mathematics, a sequence is an ordered list of elements; concepts of convergence, monotonicity, and limits rely on index in the natural numbers.

In computer science, sequential execution refers to instruction processing in a fixed, one-after-another order unless parallelism is introduced; algorithms can be described as sequential or parallel.

In data storage and computing hardware, sequential access refers to reading data in an ordered stream, as with magnetic tapes or streamed I/O, in contrast with random access.

In electronics, sequential circuits maintain state across time using memory elements such as flip-flops and latches. They implement counters, registers, and state machines; this contrasts with combinational circuits where outputs depend only on current inputs.

In statistics, sequential analysis evaluates data as it accumulates and can stop early; methods such as the sequential probability ratio test (SPRT) and group-sequential designs guide decision making in trials and quality control.

Other uses include describing events in time, scheduling, or storytelling that unfold in a sequence. The term is often contrasted with parallel or random, depending on whether processes occur in a fixed order or simultaneously.