Person is a fundamental idea in grammar. It is based on the fact that any act of communication requires two participants, and most mention a third. These categories are called the first person, the second person and the third person.
- The First person is the one who is talking - 'I'.
- The second person is the person who is being spoken to - 'you'.
- The third person is the one that they are talking about - 'her', 'him', 'it' or 'them'. (Notice that in grammar, the 'persons' do not have to be human beings.)
In addition, each person can be either
- singular (i.e. there is only one - 'I' in the first person) or
- plural (more than one - 'we').
In English, the grammatical concept of person applies most to personal pronouns; there is also a table of personal pronouns, along with a separate article about archaic personal pronouns used in older English. The idea of person is also helpful in studying verbs.
In academic writing, try to avoid using the first and second person. As so often, the best advice to a writer is 'think of your audience'. If you are not sure what person to write in - and especially if you have been marked wrong, and do not know why - ask your Supervisor. Good writers try to think of the audience they are writing for. For a note on a particular grammatical problem in writing formal English, you may want to see Agreement of preposition with pronoun.
Some oddities can arise in trying to sound too stiff and academic. I once saw the following in an academic book (Robbins, 2003), Acknowledgements, p. xii: "... my thanks to them. Our thanks are also due to our husband, Richard Andrews, who remains just as the doctor ordered." Here, the use of the formal 'we' with the most intimate of relationships, marriage, rings a very false note in the minds of subtle readers. This is reinforced by the fact that the (individual) writer is happy to use 'my' when thanking her more professional helpers.