In grammar, a conjunction (abbreviated or ) is a part of speech that connects words, sentences, phrases, or clauses. A discourse connective is a conjunction joining sentences. This definition may overlap with that of other parts of speech, so what constitutes a “conjunction” must be defined for each language. In general, a conjunction is an invariable grammatical particle, and it may or may not stand between the items it conjoins. The definition may also be extended to idiomatic phrases that behave as a unit with the same function, “as well as”, “provided that”. A simple literary example of a conjunction: “the truth of nature, and the power of giving interest” (Samuel Taylor Coleridge’s Biographia Literaria) Conjunctions may be placed at the beginning of sentences. But some superstition about the practice persists.