If you had an account with $1,000.00 in it, all of it is “equity”.
When you open a trade, you use part of your “equity” to hold that trade open.
That part you used to open the trade is “used margin”.
Subtract that from your equity to get “usable margin”. That is the amount left over that your trade gains or losses operate in. If your trade is losing, you chew into that usable margin, and see a decrease in your equity.
If your trade is profitable, you see your usable margin, and equity rise.
Thanks a lot, just another question: so I get a margin call when my equity becomes less than used margin, it means that my usable margin must fall below 0? Thanks a lot again