When writing your essay that is extended you use language this is certainly formal and academic in tone.
Differences Between formal and informal Essays
The chart below provides you with some notion of the differences between informal and formal essays. See the box below for examples of the differences in tone in informal and formal essays written on identical topics. A PDF of the chart, and the examples below, is in the box to the right, along with a listing of tips for avoiding writing that is colloquial.