BibTeX is reference management software for formatting lists of references and makes it easy to cite sources in a consistent manner, by separating bibliographic information from the presentation of this information, similarly to the separation of content and presentation/style supported by LaTeX itself. (source)
• BibTeX databases are files that use .bib extensions, not .tex like LaTeX files.
• Most reference managers (e.g. RefWorks, Zotero, BibDesk, etc.) allow you to export a BibTeX database.
Web of Science - In brief, with a citation you want to save, at the bottom of the article information page, select the drop down box Save to other Reference Software, and select BibTeX.