An editor of scientific books must pay particular attention to spelling and punctuation because scientific writing demands accuracy, consistency, clarity and precision. A small spelling or punctuation error may alter the meaning of a technical statement, create ambiguity in a numerical value, or even lead a reader to misunderstand a scientific procedure. Unlike general publishing, scientific editing involves specialised terminology, units, symbols, abbreviations, chemical names, mathematical expressions and references. Therefore, an editor must be familiar not only with general English usage but also with the conventions followed in scientific and technical publishing. Spelling conventions are important because scientific texts frequently contain specialised words derived from Latin, Greek and other languages. The editor should follow a recognised dictionary, style guide or house style consistently. British and American spelling conventions differ in several respects. For example, British English generally uses “colour”, “behaviour”, “centre”, “organisation” and “labour”, whereas American English uses “color”, “behavior”, “center”, “organization” and “labor”. Neither system is inherently incorrect, but an editor should ensure that one system is used consistently throughout a book. Switching between “organisation” and “organization” without a deliberate reason gives an impression of poor editorial control. Scientific terminology also requires careful spelling. Words such as “photosynthesis”, “electromagnetic”, “microorganism”, “biotechnology”, “neurophysiology” and “spectrophotometer” must be checked accurately. Scientific editors should not rely entirely on ordinary spell-checking software because specialised terms may be incorrectly flagged or, conversely, an incorrectly spelled scientific term may be accepted if it resembles another dictionary word. The treatment of prefixes and compound words is another important issue. Terms may be written as one word, as two words, or with a hyphen depending on established scientific usage. For example, “antibody”, “microorganism” and “semiconductor” are normally written as single words, while certain expressions may require a hyphen, such as “dose-response relationship” or “temperature-dependent process”. The editor should consult authoritative scientific sources rather than applying a general rule mechanically. Hyphenation is particularly significant in scientific writing because it can affect meaning. Consider “small animal experiments” and “small-animal experiments”. In the second expression, the hyphen makes it clear that “small-animal” functions together as a modifier. Similarly, “high pressure system” may be unclear, whereas “high-pressure system” is more precise when the phrase is used adjectivally. However, unnecessary hyphens should be avoided. An editor must therefore distinguish between established compounds and temporary compound modifiers. Capitalisation is also governed by scientific conventions. Common nouns should generally not be capitalised merely because they occur in a scientific context. For example, “cell”, “organism”, “enzyme” and “protein” are normally written in lower case. Proper names, specific geographical names, named laws and institutions may require capitals. Scientific names of organisms follow a special convention: the genus name begins with a capital letter and the species name with a lowercase letter, usually with both italicised, as in *Escherichia coli* or *Homo sapiens*. After the first full mention, the genus may be abbreviated, for example, *E. coli*, provided that the abbreviation is unambiguous. Chemical names and symbols also require careful treatment. The editor must distinguish between chemical symbols and ordinary abbreviations. For example, “Na” represents sodium, while “NA” does not have the same meaning. Similarly, “Co” represents cobalt, whereas “CO” represents carbon monoxide. The