If you choose not to bail someone out of jail, they will typically remain in custody until their case is resolved or until they are released on their own recognizance by the court.
The decision of whether to bail someone out of jail is a personal one, and there may be a variety of reasons why you choose not to do so. For example, you may not have the financial means to post bail, you may not feel comfortable assuming the risk associated with posting bail, or you may not believe that the person is likely to show up for all of their court appearances.
If you do choose to bail someone out of jail, you are assuming certain legal and financial obligations. Specifically, you are responsible for ensuring that the person appears at all required court hearings, and if they do not, you may be held liable for any fines or penalties associated with their failure to appear.