The document discusses Type 1 conditional sentences which refer to possible present or future real-world conditions and their probable results. A Type 1 conditional uses the simple present tense in the if-clause and simple future tense in the main clause. The order of the clauses can be rearranged while maintaining the same meaning. Examples are provided such as "If you drop that glass, it might break" and "I may finish that letter if I have time." Modals can also be used instead of future tense to express degree of certainty or permission regarding the outcome.