Matthew Collins

Each type of visual aid has pros and cons that must be evaluated to ensure it will be beneficial to the overall presentation. Before incorporating visual aids into speeches, the speaker should understand that if used incorrectly, the visual will not be an aid, but a distraction. Planning ahead is important when using visual aids.
It is necessary to choose a visual aid that is appropriate for the material and audience. The purpose of the visual aid is to enhance the presentation.

Smoke is a collection of airborne solid and liquid particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass.
It is commonly an unwanted by-product of fires (including stoves, candles, oil lamps, and fireplaces), but may also be used for pest control (fumigation), communication (smoke signals), defensive and offensive capabilities in the military (smoke-screen), cooking, or smoking (tobacco, cannabis, etc.).

Many books have been written about Silicon Valley and the collection of geniuses, eccentrics, and mavericks who launched the "Digital Revolution"; Robert X. Cringely's Accidental Empires and Michael A. Hiltzik's Dealers of Lightning are just two excellent accounts of the unprecedented explosion of tech entrepreneurs and their game-changing success.

But Walter Isaacson goes them one better: The Innovators, his follow-up to the massive (in both sales and size) Steve Jobs, is probably the widest-ranging and most comprehensive narrative of them all. Don't let the scope or page-count deter you: while Isaacson builds the story from the 19th century—innovator by innovator, just as the players themselves stood atop the achievements of their predecessors—his discipline and era-based structure allows readers to dip in and out of digital history, from Charles Babbage's Difference Engine to Alan Turing.