What does "summarize" mean?
When we summarize, we are setting forth all of the important elements in a text. We do this slightly differently for fiction and for non-fiction. This also depends upon whether we are summarizing a chapter, an article, or an entire book and any length requirements we may be subject to for a summary assignment.
When we summarize a fictional text, we usually provide the names of the main characters, the setting, which is time and place, and a brief overview of the plot. Generally, a plot involves some sort of conflict, so a summary should state what the conflict is and how it is resolved. A summary is not the same as a literary analysis, since a literary analysis is meant to address topics such as the themes of a book. A summary can be helpful, though, in writing a literary analysis, just to give the reader a brief overview of the literary text before analyzing it. Sometimes an assignment involves just a chapter summary. In that event, the method is the same, to briefly explain characters, setting, and what happens in the chapter. Depending upon whether you are expected to write a one-paragraph summary or perhaps a one-page summary, your approach will remain the same but you could add a few more details for the latter.
To summarize a non-fiction text, you need to ascertain what the writer's main idea is, the idea he or she wants you to take away after reading the text. Then you need to understand how the writer has supported this idea. These are all you need for a non-fiction summary. Again, you are not analyzing the text, just providing a brief overview of what the writer has to say. If the writer has provided statistics, for example, or anecdotal details, these should be explained briefly. If the writer is providing a historical account, this, too, can be explained in a summary, just hitting the high points of what the writer has written. A short article can probably be summarized in a paragraph, while a summary of a non-fiction book might take a page.
The ability to summarize is an important academic skill, as well as an important skill on the job. When we can glean from our reading what is most important and put it in our own words, we have gained mastery of the material, which is the whole point of reading it in the first place!