To glance means to look at something quickly and briefly, then look away. When you glance at the clock during class, you're not staring at it for ten seconds. You're checking the time with a swift look that takes maybe half a second. When a baseball player glances at first base before pitching, he's stealing a quick peek to make sure the runner isn't taking too big a lead.

A glance is different from a stare or careful examination. If you glance at your homework, you're not really reading it closely. If you glance through a book, you're flipping pages and catching bits here and there, not studying every word. People often glance at things when they're busy or distracted, or when they don't want others to notice they're looking.

The word can also be used as a noun. You might understand something at a glance (immediately, without needing to look carefully), or catch someone's problems at first glance (right away, upon seeing them for the first time). When something is obvious at a glance, you don't need to investigate further to understand what's going on.