A more thorough explanation:

A cosurety is a person who shares the cost of performing suretyship obligations with another. In other words, a cosurety is someone who agrees to be responsible for paying off someone else's debt or fulfilling their obligations along with another person.

For example, let's say that John and Jane are both cosureties for a loan that their friend, Bob, took out. If Bob is unable to pay back the loan, both John and Jane are responsible for paying it off. They share the cost of fulfilling the obligation as cosureties.

Another example could be in a construction project where multiple contractors are hired to complete different parts of the project. Each contractor may have a cosurety who shares the cost of fulfilling their obligations in case they are unable to complete their part of the project.

These examples illustrate how a cosurety is someone who shares the responsibility of fulfilling an obligation with another person. They are both equally responsible for fulfilling the obligation, and if one person is unable to do so, the other person must step in to cover the cost.