Coverslips are used to cover the microscope slides and they are nothing but a small piece of glass usually cut int a square or rectangular shape.
The function fo the coverslip is to make the specimen flat that is to be viewed under the microscope as well as prevent any kind of evaporation to take place for the sample.
Further, the coverslips protect the samples mounted onto the slide from dust and other environmental factors that can lead to the spoilage of the specimen.
Whenever a sample is mounted onto the slide, the coverslip needs to be paced gently at an angle of 45 degrees otherwise it can lead to the formation of air bubbles.
