An essay is a relatively short piece of writing dealing with any one subject. Sometimes it is personal, about a significant event, for example. Or you can be arguing about two contrasting viewpoints.
Lamb rambles, where you should be focused. Lamb’s introductions do not summarise his essays, yours should. Well, I do not think you should be boring!
It tells the reader what to expect, and what to look for. The body or content of the essay will contain the points you want to make, with supporting arguments and evidence. It must show the reader that you know your subject.
You do this by explaining the subject to the reader. I look here at some of the other forms of writing that students are asked for, and how they relate to essays. Students studying some subjects may never be asked to write an essay. Parts of essays, like the summary, may also be forms of writing in their own right. Students may be asked to carry out empirical research, or conduct a project like designing something.
Summaries, Abstracts and Reviews are interrelated forms of writing. The word is used for summaries that appear at the beginning of academic papers, journal articles or books, and for similar summaries in collections of Abstracts. Sometimes students are asked to write summaries of books or articles. You will try to convert a large number of words into very few, so you will look for the main points.