English is the official language. It is what most schools teach in, what news is written in, and what people from different parts of Nigeria use to talk to each other. But at home, most children speak a different language with their family.
The three biggest local languages are Hausa, Yoruba and Igbo. Hausa is spoken mostly in the north - around 50 million people use it every day. Yoruba is spoken in the southwest, including around the huge city of Lagos. Igbo is spoken in the southeast. Each one has its own greetings, its own songs and its own way of telling jokes.
Speaking more than one language is normal across most of the world - about two-thirds of all people use more than one language every day. People who speak two languages are called 'bilingual'. People who speak many are called 'multilingual'.
When you learn a new language, you don't just learn new words - you learn new ways of seeing things. In Yoruba, the word for 'good morning' (E kaaro) takes a moment to say properly, because greetings are very important. In Hausa, you might be asked 'Sannu, lafiya?' which means 'Hello, are you in good health?' - a kinder hello than just 'hi'.