convergent sequence is a sequence when n closes to infinite, the evaluate of sequence closes to a natural number which less than infinite. For example, {1,1/2,1/3,1/4,1/5,1/6…….1/n}

divergent sequence is a sequence when n closes to infinite, the evaluate of this sequence is infinite. for example，{1,4,9,16,25,36…….n^2}

convergent series is a series that the sum of this series is closes to a number which is less than infinite. For example, the sum of 1/n^2

divergent series is a series that the sum of this series is infinite, for example, the sum of 1/n