Forex & MetaTrader
The spread is the difference between the ask and the bid price of an instrument; it is the immediate cost of opening and closing a position and it widens when liquidity is thin, at market open, around news, and on exotic or low-volume symbols.
Spread is paid on every trade before any market movement, so it caps how short-term a strategy can be: a scalping signal with a 5-pip target on a symbol with a 3-pip spread has most of its edge eaten before it starts. Spread is also a risk: brokers widen spreads sharply at news, which can trigger stops that the mid price never reached and turn a limit-style entry into a poor fill. A signal channel's advertised results rarely include the spread its followers actually pay.
On MetaTrader 5, AlgoVesta reads the live bid and ask from the terminal and can block a signal when the spread exceeds the limit you set for the bot, recording the block with its reason instead of entering at a bad moment. Because fills come from the venue and stops are derived from the actual fill, the spread is reflected honestly in the recorded entry and in the distance to the stop. The demo page shows measured spreads from real quotes rather than an assumed value, and it is labelled as the lowest measured spread, not as a claim about the whole market. On crypto exchanges the spread is set by the order book, and the fill reported by the exchange includes it. Pip sizes are read per broker symbol, including suffixes, so a spread on gold is not miscounted by a factor of a thousand. See bid/ask and Forex on MetaTrader.
A bot has a spread limit of 2.5 pips on EURUSD. At 15:29 the spread is 0.8 pips and a signal executes normally. At 15:30 a data release widens the spread to 6 pips; a second signal arriving at that moment is blocked with the spread reason and appears in the log. At 15:34 the spread is back to 1 pip and the next signal executes.