Mitosis is cell division mainly for the purposes of growth, maintenance, and healing. A cell that divides mitotically should not only be genetically identical to its parent cell, but also retain the epigenetic tags which identify how it should behave, i.e. what "type" of cell it is. Mitosis produces two daughter cells from one parent cell.
In meiosis, the parent cell is dividing for the purpose of reproduction alone. While the parent cell has a full set of chromosomes, each daughter cell has half the number of chromosomes found in a normal cell (whatever this number happens to be for the given species). During meiosis, the chromosomes are able to swap their contents, ensuring the resulting cells have chromosomes with unique combinations of maternal and paternal features, statistically leading to increased variety in offspring. Meiosis involves two separate cell division events, which result in four cells rather than two. Of the two cell division types, meiosis is less frequent—or at least a lesser proportion—because the body is, on average, overwhelmingly devoted to maintaining itself.