There are two terms on Wiktionary used when we are including information from external sources: quotations and references.
Quotations, also called citations, are added to entries in between definitions; they are also added (particularly if they are very numerous) to the Citations pages that accompany each dictionary page. They exist to demonstrate the usage of a word. Conventionally, quotations are accompanied by a definition tailored and evaluated to encapsulate the overall meaning of the use-instances. Wiktionary upholds a criterium of at least three use-instances per definition, as per WT:ATTEST.
References are used to refer to information about words written by others. They are mainly used in the Etymology, Parts of speech, and Usage notes sections to demonstrate that the contents have not been fabricated. However, references are generally not added in between a definition and a quotation, for this would require a cited definition and Usage note to originate from the same reference, which in turn makes mentioning the quotation redundant.
References can be added to an entry using footnotes or regular wikitext. <ref> tags or reference templates, and the contents of these tags will be displayed at the bottom in a ===References=== section that contains the <references/> tag. Each <references/> tag will show the information in preceding <ref> tags up to the previous <references/> tag, if one exists. A group= parameter is allowed if multiple <references/> groups are used per entry, but otherwise not needed. See Help:Footnotes for more information about how to use this feature.