Is it a must for designers to leave their contact details on client's work?

[Stardom22]

For me l have always been seeing some signatures, contacts among other designer's details on walls and other client's work spaces. Is it professionally to be done that way?

 

[kit_hung]

Leaving contact or signature on client's work a good way to advertise yourself. But it must be done by agreement. signature should be kept to minimum so not to detract from the beauty of the work you did. Order to create respect and appeal.