An abstract is a brief summary of the main findings and conclusions of a scientific paper, talk, or poster. You might not find this exact definition in the dictionary, but the idea of a summary of points is what we are looking for.
For an introductory physics lab report, an abstract might look like this…
Light passing through a transparent medium can be refracted. We used Snell’s Law to determine the index of refraction for an acrylic block. We found the index of refraction to be 1.53, which is within 2.00% of the expected value. Knowing the index of a refraction is important for the design of optical systems, particularly those involving lenses.
(Please note that this would be an abstract for a very simple lab. In my courses, the refraction section is just a part of a larger lab that investigates both refraction and reflection. The actual one you might write for the lab would be longer.)
If you present a talk or a poster at a scientific gathering, you will need to write an abstract as part of the submission process.
Journal abstracts are accessible to everyone on the journal’s website. If you search from your library’s website, you can usually see abstracts, even if a subscription is required to read the paper.
The abstract shown here is all you can see without a subscription to the Journal of Vacuum Science and Technology.
Once a scientist has a paper, we use the abstract as a synopsis of the paper. We might need to reference 20 or more papers in a paper we write. The synopsis helps us remember what each paper is about.
Spend a bit of time working on your abstract. It is helpful to start writing it even before you begin the experiment. However, you do need to go back and add your final results.