Good till canceled (GTC) lets an order remain available for execution instead of expiring merely because it did not fill immediately. It is commonly applied to limit orders, allowing a trader to wait for an acceptable price.
What remains after a partial fill
Suppose a GTC buy limit order requests ten tokens at no more than $4 each. If three execute and no further matching quantity is available, the remaining seven can stay on the order book. Subsequent trades must still respect the limit. The order need not execute at one time or at one exact price.
A GTC limit order can also execute immediately when compatible liquidity exists; GTC does not mean maker-only.
Managing an outstanding order
An old order may become undesirable as the market or trading plan changes. Review it explicitly rather than assuming that logging out removes it. A cancellation request cannot reverse quantities already executed, and a fill may occur before cancellation takes effect.
GTC is subject to platform restrictions and possible administrative cancellation. Check the actual status and any reserved balance before placing a replacement order.