Internships are great opportunities for students to get exposure to different industries and jobs before making the decision on where they would like to work. They are a great talking point when applying for jobs (as they demonstrate experience in a professional environment) and very often end up being the same job you start out in when you leave school. Most schools have a career center which lists job postings, but it is also good to participate in your company's career fair to start introducing yourself to the Recruiters (who will often be the ones deciding who gets interviews for the full time jobs). If your school doesnt have a career center or career fair, very often the company websites will have sections where you can get more information on applying for employment at the company, including for internships. Very often your professors will have professional contacts that they can get you in touch with to get more details on applying for these opportunities.
Participating in an internship is a great way of developing your skills in a certain career field that interests you. It is also an amazing way to network and form strong professional relationships with others in the career field that you wish to pursue. I would suggest researching companies that interest you and then applying on their website if you find any internships that you feel you would enjoy.
Internships are golden opportunity to get you into the work industry. It gives you opportunities to apply your studies. Depending on your major, certain major requires certain hours of internship to graduate. Most university or college have a placement program or the head of departments can give you good guidance to companies who hire interns.