Four possible categories of oral presentations include:

Memorized,
Read,
Impromptu, and
Slide-based.

Each of these have varying degrees of:

• Preparation time,
• Organization,
• Correctness,
• Interaction, and
• Improvisation.

Memorization

This requires the most significant amount of preparation time, is highly organized and correct, allows for some interaction with the audience, and minimal improvisation.

Reading

A read speech requires less preparation time than memorized speeches but reduces both interaction and possibility for improvisation.

Impromptu

Impromptu speeches require minimal preparation, are likely to be unorganized and incorrect, but allow for a significant amount of interaction with the audience and improvisation.

Slide-based Presentations

A slide-based presentation requires more preparation time than a read speech, is equally organized, has a reasonable expectation of correctness, allows for interaction with the audience, and allows for improvisation.