An e-reader, also called an e-book reader or e-book device, is a mobile electronic device that is designed primarily for the purpose of reading e-books and digital periodicals. An e-reader is similar in form, but more limited in purpose than a tablet.-book reading is increasing in the US; by 2014 28% of adults had read an e-book, compared to 23% in 2013.
1 Developmental biology â The study of the processes by which an organism changes from a single cell into a mature, multicellular individual.  Epigenetics (pronunciation) â The study of heritable changes in phenotype caused by mechanisms other than the alteration of nucleotide sequences.
Validity, accuracy, and social mechanisms ensuring quality control, such as peer review and repeatability of findings, are amongst the criteria and methods used for this purpose. Natural science can be broken into two main branches: life science (or biological science) and physical science. Physical science is further broken down into branches, including physics, astronomy, chemistry, and Earth science. All of these branches of natural science are divided into many further specialized branches (also known as fields), and each of these is known as a natural science.