**Therefore** is a conjunctive adverb that expresses a result, consequence, or inference. It is used to show the relationship between two clauses in a sentence. Here are some examples of its usage:
1. I forgot to buy milk, **therefore** we have to go to the store now.
2. She studied hard for the exam, **therefore** she got a high grade.
3. The weather is nice today, **therefore** we should go for a walk in the park.
4. He overslept, **therefore** he missed his bus and was late for work.
5. We ran out of sugar, **therefore** I need to buy some at the supermarket.
6. The company has lost a lot of money, **therefore** it might have to lay off some employees.
7. I didn't prepare for the meeting, **therefore** I was unprepared when it started.
8. The car broke down, **therefore** we had to call a tow truck.
9. She didn't eat breakfast, **therefore** she was hungry by lunch time.
10. He forgot to charge his phone, **therefore** it died during the meeting.