If you submit a resume either online or through a recruiter, that resume will go in a pile which will be sifted through by recruiters. Recruiters are looking for a good educational background and amazing project/work experience. The recruiters take the passing resumes and hand them out to engineers, who pick from that pile people they want to interview. Interviews for interns are a 30 minute technical phone interview, where a manager will ask you technical and theoretical questions, as well as detailed questions about any experience you put on your resume. If you pass, they will usually extend an offer to you within a week.