reading titles and headings,and trying to get an overview of what lies ahead in reading passageis called

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See definition #2.

The process you are describing is called "skimming." Skimming involves quickly reading the titles, headings, and subheadings of a text to get a general sense of the content and organization. By skimming, you can preview the main ideas, key points, and overall structure of a passage before diving into a detailed reading. This technique helps you create a mental map of the passage and understand what to expect as you start reading. Skimming is particularly helpful in quickly assessing whether a text is relevant to your needs or if it provides the information you are looking for.