Turing Machine

Each cell of a tape is marked with a symbol. Each TM defines a finite set of possible symbols.

A TM always "is in" a state. We use capital letters for states: A, B, C, ... Each TM defines a finite set of possible states.

The tape is the "memory" of a TM. It is a strip (series) of cells. It is considered to be horizontal, from left to right. It is unlimited at both ends, i.e. can contain an unbounded amount of non-blank symbols.

Cells are the constituent part of a tape. Each cell is marked with a symbol.

The read/write head of a TM identifies one cell of the tape, which is first read from and then written to as part of the action performed for a transition.

Transitions are part of the definition of a TM. This is, what a TM "does". A transition maps an input condition (state and symbol) to an output action (symbol, move and state). Cf. step.

An action is the output part of a transition. It specifies the output symbol to be written to the cell under the head, the move of the head, and the output state.

Either "left" (L or <) or "right" (R or >).

A move is that part of a transition action, which specifies how the head is moved along the tape.