The four modes of speech delivery are memorization, manuscript, impromptu and extemporaneous. Each term refers to the method used by the speaker in delivering a speech.
Memorized speeches are delivered after extensive rehearsal and memorization. Generally, the speaker writes a speech and attempts to recite it word for word, leaving little room for adaptation. Memorization is considered the most difficult mode, and it is not recommended for novice speakers.
Reading a manuscript of a speech gives the speaker the advantage of not omitting vital information and staying focused, but it takes away from other important aspects, such as eye contact. Impromptu speeches work well for quick-thinking speakers, but they leave open the possibility of losing focus or disorganization.
Extemporaneous speeches combine some elements from the previous three modes. It involves a lot of preparation and outlining. Note cards are often used to stay organized while adapting the content to the audience.