counter: A variable used to count something, usually initialized to zero and then incremented.
empty string: A string with no characters and length 0, represented by two quotation marks.
format operator: An operator, %, that takes a format string and a tuple and generates a string that includes the elements of the tuple formatted as specified by the format string.
format sequence: A sequence of characters in a format string, like %d, that specifies how a value should be formatted.
format string: A string, used with the format operator, that contains format sequences.
flag: A boolean variable used to indicate whether a condition is true.
invocation: A statement that calls a method.
immutable: The property of a sequence whose items cannot be assigned.
index: An integer value used to select an item in a sequence, such as a character in a string.
item: One of the values in a sequence.
method: A function that is associated with an object and called using dot notation.
object: Something a variable can refer to. For now, you can use “object” and “value” interchangeably.
search: A pattern of traversal that stops when it finds what it is looking for.
sequence: An ordered set; that is, a set of values where each value is identified by an integer index.
slice: A part of a string specified by a range of indices.
traverse: To iterate through the items in a sequence, performing a similar operation on each.