Day trading lives inside a single session. A position can last a few minutes or a few hours, but by the time the session closes, the algorithm has flattened everything. Nothing carries over to the next day. No overnight risk, no surprise news at 3 AM moving an account nobody is watching.
In the US, FINRA gives the style a formal name on securities accounts. The pattern day trader rule kicks in when a margin account executes four or more day trades within five business days. Once flagged, the account has to maintain at least 25,000 USD of equity.
Frequency sits in the middle: a handful of positions a day, not dozens. The trade-off versus scalping is simple. Each position aims for more, so costs hurt less. Versus swing trading, it is the reverse. You miss the multi-day moves entirely, because you are out by the close.
What day trading really buys is sleep. The account is flat when you go to bed, so whatever happened in Asia overnight has nothing on it to move. For algorithmic strategies that need clean session boundaries and predictable session liquidity, this is the natural shape.
Day-trading strategies tend to concentrate on the most liquid sessions and instruments. London and New York for forex majors. Quiet hours and exotic pairs are not where this style lives. Javlot strategies labelled as intraday flatten by close by design.