Either refers to any one of the two things or people. Either is always considered singular in a sentence. Either … or is a correlative conjunction. We use either … or for connect things which are the same types, phrases, clauses or words.
- Either he or she cooks dinner.
- Either Mark or Samuel will go.
- You can either come with me now or walk home.
- They don’t have enough time. They can either have breakfast or have a shower.
- You can either call me at home or the office.
- I’ll either write to you or phone you next week.