To liaise means to cooperate or communicate with an individual or organisation on something of mutual benefit or common interest. When you liaise it means to maintain communication in order to work together towards a common goal.

1. Frank is working as a liaison between the buyer and seller in order to help smooth over any problems that may arise while they are negotiating their deal.
2. I am liaising with the local authorities to find a solution to illegal dumping.

1. Someone will be assigned to liaise with the manufacturers to ensure that the product fits our criteria, and meets our standards.
2. The company is liaising with local groups in order to win approval for a new factory to be built in the area that would provide hundreds of new jobs.

1. We hope the local community and the police can liaise to create a neighbourhood watch.
2. The school will liaise with students on their progress throughout the year.