When writing a summary, it is important to include only the main ideas and leave out supporting details.
A summary is a short informational text that includes the main ideas of a piece of writing. Regardless of what you are summarizing, there are some key tips you need in order to write a successful summary. First of all, you should remember that what you leave out is just as important as what you leave in. What I mean by that is that you do not want to overburden your summary with a bunch of unnecessary details. For example, if you are summarizing a book, do not tell us what the character had for breakfast unless that is a key plot detail that is very important to the story. Too often, summary writers just include too much. Keep it short and simple. Stick to the main ideas.
When writing a summary of a book, I suggest beginning by writing everything you remember. Then, go through with a highlighter and highlight the key details. Those are what you will leave in. What is not highlighted will be left out. Also, do not include commentary in a summary. You do not give your personal opinion. There is a place for that, but not in a summary. A summary is just the facts. It should be objective, meaning that you do not include yourself in it.
Another good way to write a summary is to make a leave in/leave out list. Make a chart, like a T-chart. As you think of ideas, on one side of the chart write ideas of what you want to leave in to the summary, because they are important, and on the other side write ideas of what you want to leave out, because they do not seem important.
First, you must ask yourself what the word summary means. Summary indicates that you give a brief overview of a story, event, or situation. For example, if someone asked you how was your weekend, you would not give then a detailed play by play for every minute that elapsed. Instead, you would hit the high points that occurred from start to finish.
So when a teacher prompts you to summarize a story or novel, do the same. State all the major events in chronological order, remove unnecessary details, and stick to the facts. Understanding these few tips, your summary will be concise and correct.
As a student myself who is also asked to make summaries, this is what I do.
First, the introduction should be straight on. The first sentence should already state what the whole assigned reading is all about and the following sentences should give further details to the first one. The succeeding paragraphs should just point out the important details and should not be discussed very long. To end a summary, point out interesting conclusions and what the text found out.
As mentioned in other responses, the summary serves to communicate the main points of some other (oftentimes much longer) piece of work. The approach that helps me narrow down an entire passage to a few points is to consider how I would explain it to a friend. If you think about how you do this in conversation, you might be surprised to find that you naturally start with the broadest idea of the passage, or the main idea. This translates well to what the topic sentence of your summary should be. Then, you'll probably get a little bit more detailed and present "mini summaries" of the different sections of the larger passage. These sections might be inherent in the work (maybe you are summarizing a textbook chapter and the sections are broken like 12.1, 12.2, etc.) or they can be a product of how you interpreted the work (for a novel, you might break it into "presenting characters/describing setting", "rising action", "dramatic climax", "concluding action").