Autocomplete fields (select2) were introduced in Caldera Forms 1.2.3. They are multi-select fields that look like text inputs, but autocomplete to a set of pre-defined options. Those options can be set from the UI, or autopopulated, like any other select field.
Autocomplete fields can optionally be set to accept multiple values in the same field. This field type is an excellent tool for avoiding long drop down lists.