Binding off is the process of securing a row of a swatch so that it doesn't unravel. This can be used on the last row to finish the swatch, in which case it is accompanied by a tag. Alternatively, it can be used on an intermediate row to flatten a tube. This is done by knitting through a loop and transferring it to its neighboring loop, and repeating this process. This connects the loops in the row together, preventing them from unraveling.
Bind-offs for tubes can either leave the tube open or closed. To achieve a closed bind-off, the loops on one bed can be transferred to the other bed and bound off like a sheet.