You mostly apply for Co-op jobs through Waterloo's job bank, Jobmine. You can also look outside Jobmine if you wish, but most people stick to using this bank. You start applying for jobs in the term before your work term (so if you have a work term in Summer, you will start applying during the Winter term). The job postings are separated into 2 main rounds - the first (AKA main) round and the continuous round. In the main round (which begins around the end of the first month) there are often up to around 3000-4000 job postings. You can apply to a maximum of 50 jobs, and you only have around 3 days or so to apply, so make sure you mark those dates on your calendar! Afterwards, employers start screening and interviewing you and depending on your performance, they will hand out offers or ranks. A rank means that they liked you, but you were not their top choice. In the last week of the second month, there is a "match weekend" in which you get to see your ranks and offers, and pick which jobs you want by also ranking the jobs from 1-9. The algorithm is designed such that it takes your rank, the employers rank (an offer is considered rank 1), and then adds them; the person with the lowest combined number is then matched with the job! Thus, if you got an offer and rank it 1, you automatically get the job.