Depending on your time frame. You draw a line from the lowest low to the highest high and that is swing trading. You can usually see the last high or low and draw a line. You do not know when the next low or high will be and you will be in the trend though.
At least you don´t know, unless you have some method of guaging that. Different multiple moving averages is a simple way of doing it. When the prices crosses and direction reverses that can be it.
I associate "swing trading" with long term changes in the business cycle as in "the economy swings from the bottom of a recession to the peak of economic recovery."
A trader might buy a stock as the economy begins growing and stock price values increase. A trader might sell as a recession begins and stock price values decrease.
I also associate "swing trading" with certain price behavior. Price values sometimes fluctuate within a trading range. I mark on the attached chart the upper price limit of some trading ranges with green lines, the lower price limit with red lines. Price values sometimes change from one trading range to another trading range. That transition may be referred to as a "swing." Prices tend to show two behaviors - stability and instability. Stability is associated with trading ranges, instability associated with price breakouts (transitions to another trading range).
This description is just my opinion, the lines I draw are arbitrary.
I like to think of that as the step ladder approach. Works going up and down. Higher bottoms and you are in a trend. Lower pullback tops and you are in a downtrend. Which part of it you treat as a swing trade is up to you.
The difficult part is guessing the end of the swing before it happens.
Day trading, no overnight exposure
Swing trading, a few days of exposure
Position trading, riding the intermediate term trends, trades run for 1-120 days.