επειδή

In a sentence

• Δεν πήγα στη δουλειά σήμερα επειδή ήμουν άρρωστος.

  I didn't go to work today because I was sick.

  In this sentence, 'επειδή' is used as a conjunction introducing the reason or cause behind not going to work.

• Μίλησα με τη δασκάλα σου επειδή ανησυχούσα για τους βαθμούς σου.

  I spoke with your teacher because I was worried about your grades.

  Here, 'επειδή' provides the reasoning for why the speaker contacted the teacher.

• Δεν μπορούσα να κοιμηθώ επειδή οι γείτονες έκαναν φασαρία.

  I couldn't sleep because the neighbors were noisy.

  In this context, 'επειδή' links the inability to sleep to the cause of the neighbors being noisy.