An internship can provide career-building experience and be a stepping stone to your dream job. The essay gives you a chance to express your personality beyond what can be gleaned from other aspects of the application. Think of it as a written interview and use it as an opportunity to convey your passion for the field and personal motivations. A well-crafted interview can separate you from the other candidates by demonstrating your strength in written communication.
Start with an attention-grabbing opening sentence. Whoever is reading your essay will likely be reading many of them, so you need to establish yourself immediately as special by revealing a detail that is relevant but interesting and unique. Your introductory paragraph should be specific and directly related to the internship. For example, if you're applying for a veterinary internship, mention your experience as a pet foster parent or classes you've taken related to animal behavior and well-being.