The document discusses sequences, specifically arithmetic and geometric sequences. It defines an arithmetic sequence as a sequence where each term is found by adding or subtracting the same number to the previous term, called the common difference. A geometric sequence is defined as a sequence where each term is found by multiplying or dividing the previous term by the same number, called the common ratio. It provides formulas for calculating the nth term and sum of the first n terms of arithmetic and geometric sequences. Examples are given of identifying sequences as arithmetic or geometric and calculating terms within sequences.