1. The document describes four types of sequences: arithmetic, geometric, harmonic, and Fibonacci.
2. It provides examples of each type of sequence and how subsequent terms are calculated. For arithmetic sequences each term is obtained by adding a constant, for geometric sequences each term is obtained by multiplying a constant, and for harmonic sequences the reciprocals of the terms form an arithmetic sequence.
3. A Fibonacci sequence is defined as starting with two terms that are either both 1 or 0 and 1, with each subsequent term calculated by adding the two preceding terms.