The geometric sequence is a sequence with a common ratio. The common ratio is the ratio between the succeeding term and the preceding term of a sequence and must be equal to a constant k.
Given a sequence 2, 4, 8, 16... This sequence is geometric in nature because of a constant common ratio of 2.'
Common ratio = 4/2 = 8/4 = 2
Hence a geometric sequence is characterized by its common ratio