Some computer programs take advantage of batch processing, a mode in which the input data is compiled beforehand and submitted all at once, requiring little human intervention. This contrasts with interactive processing, where the computer waits for your input and handles it piecemeal, one data item at a time. For example, most websites employ interactive processing, whereas a large company may use batch processing to run its weekly payroll.
A data center's staff can schedule batch processing during times when the computers are otherwise idle, such as overnight. The computer operators can delay or prioritize different batches easily, depending on circumstances. Batch jobs are standard computer files containing commands, programs and data; once created, some can be run repeatedly as needed, adding convenience for the staff and helping keep processing costs low.
All of a batch job's input data must be ready before the computer can run it; this means it must be carefully checked. Problems with data, errors and program crashes that occur during batch jobs bring the whole process to a halt; the inputs must be carefully checked before the job can be run again. Even minor data errors, such as typos in dates, can prevent a batch job from running.