> <\body> In a similar way as content-based tags, environments are used to mark portions of text with a special meaning. However, while usually enclose small portions of text, environments often enclose portions that are several paragraphs long. Frequently used environments in mathematics are and , like in the example below: <\theorem> There exist no positive integers , , and with 3>, such that +b=c>. <\proof> I do not have room here to write the proof down. You may enter environments using . Other environments with a similar rendering as theorems are , , , , . You may use the macro (entered using ) in order to specify the person(s) to which the theorem is due, like in <\theorem> Under nice circumstances, we have +b=c>. Other frequently used environments with a similar rendering as theorems, but which do not emphasize the enclosed text, are , , , , and . The remaining environments , , , and can be used in order to enter multiparagraph text or code, quotations or poetry. >