Traditional 35mm slides can jazz up a presentation. They are as easy to shuffle as overheads. Slides also have some advantages as support for a speech compared with software presentation programs:
Slides can be easily carried anywhere in a small box at little risk.
Unlike having to bring computers and arrange a compatible LCD projector, slide projectors are all the same and available almost everywhere.
Because slides are less high-tech than presentation software, the audience is less likely to be distracted from the message by special effects.
Of course, slides also do not have the flexibility and creative potential that software programs do, such as the ability to insert film clips.