Originally Posted by DarkScribe
Expand on it.
Only write about what you know about.
I find it so frustrating when an author clearly does not understand something (but writes as a supposed "expert") that I won't finish the book.
For instance, an automatic revolver. (Yes I know about the Webley-Fosbery but the author didn't.) A shotgun bullet. Scuba divers breathing oxygen. Gelignite being exploded by shooting it. Parachutes that open when jumping off a twenty story building. People in a matter of seconds breaking into and hot-wiring a car that has an engine immobiliser as standard equipment. (A modern Porsche.) A classic was a writer who wrote spy story where the protagonist attached a magnetic mine to a well know Presidential yacht. The yacht in question was made of wood. The same author had a protagonist using Scuba equipment thirty years before it was invented. Another had WW1 soldiers using walkie-talkies.
I could give examples all day of people writing about things that they don't anything about. Far too many writers do no research at all.
Exactly what I meant
Another well known example is (ok it's a movie but it fits) the Matrix scene showing a traceroute running with net adresses resolved to numbers <255