と

「と」 after a person means 'together with', or the other party in something done to each other (talking, discussing, fighting): 「友達と映画を見る」, 「先生と話す」. It often goes with 「一緒に」: 「友達と一緒に行く」.

•This 「と」 tells you who you do it with; it is different from the 「と」 that joins nouns, as in 「机と椅子」.

•Two-way actions such as 「話す」, 「相談する」 and 「結婚する」 can take 「と」, and sometimes 「に」; 「と」 puts both sides on equal footing.

•If you do it alone, never say 「一人と」; say 「一人で」.