Skimming and Scanning are the two possible ways of reading techniques that enable you to locate information in a text as quickly as possible. Let me explain each to you.

Skimming
Skimming refers to the process of working your way through a piece of text quickly with the purpose of getting a general idea of the content. You do not have to read every word but focus on headings, subheadings, and key sentences.

Example :
Suppose you need to read a lengthy research report. Instead of attempting to read all of the words, you scan the abstract, the introduction, any headings and the conclusion to get an overview of the main points and to determine whether or not to read more in depth.

Scanning
Scanning is looking for general information in a text. You run your eyes over the text until you find the information you are seeking.

Example :
You would go through the pages and look at numbers and dates in a history book until you find the date you are looking for.