Fraternity recruitment differs by campus. Typically, recruitment takes place at the beginning of the fall semester. But some colleges require that the process begin at the middle or the end of the summer so students have time to settle in and get their classes in order. Many fraternities also rush in the spring, especially if they didn't meet the quota for their fall pledge class.
Rushing a fraternity is generally much more informal than rushing a sorority. Fraternities often have a formal rush like sororities, but during rush, they also have informal events. During formal rush events, a potential new member would meet with all the fraternities, and depending on the university's guidelines, visit their houses as well. Informal rush events are usually parties.
If someone's father, grandfather or other male relative was part of a certain fraternity, he may also want to join that fraternity and will be given special consideration during rush.
What are fraternities looking for? It depends on the fraternity. Recruitment is a time for a potential new member to get to know the brothers and see if the organization is something he might like to join. In turn, it's a time for the brothers to get to know the rushees and see if they'd fit in.
If the brothers decide a potential new member is fraternity material, they'll extend a formal bid. Once the new member accepts the bid, he becomes a pledge.