A gun is a normally tubular weapon or other device designed to discharge projectiles or other material. The projectile may be solid, liquid, gas or energy and may be free, as with bullets and artillery shells, or captive as with Taser probes and whaling harpoons. The means of projection varies according to design but is usually effected by the action of gas pressure, either produced through the rapid combustion of a propellant or compressed and stored by mechanical means, operating on the projectile inside an open-ended tube in the fashion of a piston. The confined gas accelerates the movable projectile down the length of the tube, imparting sufficient velocity to sustain the projectile's travel once the action of the gas ceases at the end of the tube or muzzle. Alternatively, acceleration via electromagnetic field generation may be employed in which case the tube may be dispensed with and a guide rail substituted.The first devices identified as guns appeared in China around CE 1000. By the 12th century the technology was spreading through the rest of Asia, and into Europe by the 13th century.
Punctuation is the use of spacing, conventional signs, and certain typographical devices as aids to the understanding and the correct reading, both silently and aloud, of handwritten and printed texts. Another description is: "The practice, action, or system of inserting points or other small marks into texts, in order to aid interpretation; division of text into sentences, clauses, etc., by means of such marks."
In written English, punctuation is vital to disambiguate the meaning of sentences. For example: "woman, without her man, is nothing" (emphasizing the importance of men), and "woman: without her, man is nothing" (emphasizing the importance of women) have very different meanings; as do "eats shoots and leaves" (which means the subject consumes plant growths) and "eats, shoots, and leaves" (which means the subject eats first, then fires a weapon, and then leaves the scene). The sharp differences in meaning are produced by the simple differences in punctuation within the example pairs, especially the latter.
The rules of punctuation vary with language, location, register and time and are constantly evolving. Certain aspects of punctuation are stylistic and are thus the author's (or editor's) choice, or tachygraphic language forms, such as those used in online chat and text messages.