“As is our Pathology, so is our practice,” said William Osler. Since pathology is a field, which involves processing the tissues and application of various techniques, awareness of these is very important to all the professionals who are involved in the entire process—starting from clinical diagnosis, sample collection, processing, analytical issues, diagnosis, prognosis, and finally contributing to patient management in the best possible way. The fundamental principles of living and dead is that the tissues and cells undergo immediate decay after death or surgical removal from the body. Hence in practice of pathology, it is very important and necessary to have the knowledge on preservation of tissues, appropriate method of transportation, and processing techniques keeping in mind the time at which the tests are expected to be performed on these tissues. Some of the most commonly used procedures in handling the tissues, that is, the histopathology, cytopathology, imprint cytology, squash cytology, and special procedures like immunohistochemistry, immunofluorescence, and other methods, will be discussed in this chapter. The way each tissue is handled and processed also is very important in the field of histopathlogy, which is a branch that deals with the microscopical study of the tissue specimens that are involved in the disease process. The pathologist is expected to review the sections and understand the changes that have occurred in the tissues as compared to the normal structures, which leads to the final diagnosis of various kinds of diseases. In addition to the routine staining process, the pathologist seeks the help of various stains to diagnose specific infections, uses immunohistochemistry to subclassify the tumors, uses histochemistry to identify the changes in the tissues, etc. In malignant conditions, it is important to convey to the surgeon not only about the nature of the tumor but also if it is involving the surgically resected margins and this is crucial to clinical outcome. This knowledge may also be provided through routine processing or through rapid diagnosis while the patient is on the table using frozen section processing. This gives provisional diagnosis to the surgeon during the surgical process, thus contributing to the best possible method of management. It is possible to make a tissue or cellular diagnosis using the cells obtained from the lesion. The study of cells for diagnosis, that is, cytopathology or fine-needle aspiration and cytology (FNAC), is another commonly applied procedure in pathology practice where small amount of tissue or fluid is aspirated from the swelling or cystic space or vitreous or anterior chamber for the screening or diagnosis of a disease process. In this chapter, we describe the various kinds of techniques involved in handling the tissues and also describe the ways in which the ocular tissue samples need to be handled. Though the chapter introduces the basic molecular methods involved in making a diagnosis, the advanced techniques like genetics, transcriptome profile, protein profiling, mutiomics study, etc., are beyond the scope of this chapter.