What's the meaning of W.H.T (with holding taxes) and the ways of calculating it?

WHT are the withholding taxes levied by the tax authorities on the person who is paying to vendor against the material or services recived by him at the time of payment.
Such person is deemed withholding agent and shall deposit the tax into government treasury and submit its proof to supplier.
For example "A" received goods worth $100 from "B".
These are subject to4% WHIT.
"A" shall make payment of $96 (  Payment=100*(1-.04)=$96) to "B" and shall deposit remaining $4 to government treasury and shall furnish the evidence of payment to "B"