Order types you will actually use
Market orders execute now at the available price. Limit orders wait for a better price. Stop orders trigger on a break through a level. Stop loss and take profit are server-side exits attached to a position, which is why they still work when your device is offline.
Margin, leverage and stop-out
Margin is the collateral locked for a position. Leverage determines how much collateral a given size requires. Margin level is equity divided by used margin; when it falls to the stop-out threshold the platform closes positions automatically.
The three costs of every trade
Spread is paid on entry, commission is charged per lot on raw accounts, and swap accrues every night a position stays open. A strategy that ignores any of the three will look profitable on paper and lose money in practice.