Purpose of mesh or tape on P/B?

[--tom]

What is the purpose of mesh or paper tape on plaster board? Is it to literally keep the board joins together? Or some kind of bridge?
I do know that it's necessary.
And how about the tape on fibre cement backer board in shower or wet areas, what's the tape doing?

 

[noseall]

plasterboard joint tape or scrim is there to help prevent cracking. timber or even metal stud walls are subject to some movement, therefore the tape helps deal with any differential movement between boards.

the mesh you see in aquapanel is probably reinforcing without it the board would fall to bits.

probably.

 

[--tom]

thank you for your reply.