Horizontal levels that is classic support and resistance.
Although this is not purely algorithmic concept but it works well.

Look at these 3 charts and these 3 levels.
How well price respects these levels.
🚨we are not looking to enter in trades at these levels.
We are looking for confluences to take trades.

>basic idea is to identify levels at which price has reversed in past.
>price tends to react at some specific levels and our aim is to use those levels as a confluence to our trading setups.
•These levels should be used and drawn only on htf.
•Works best on 1day and 4hr time frame.
•Not wise to draw these levels below 4hr time frame.

■HOW TO IDENTIFY THESE KEY LEVELS
>we start with 1day timeframe for macro perspective and then move on to 4hr and 1hr.
> look for levels at which price has reversed twice or more times in past.
>shortcut:- use line chart instead of bars for easy identification

■INCREASE PROBABILITY OF LEVELS
>to increase probability of reactions at these levels look to draw a box around these key levels and tag all nearby wicks with that particular box.
>use these htf levels and look for htf+ltf reversals at these levels to trade.

■IMPORTANT NOTES
1. these levels wont always work
use them as confluence to increase probability of winning
2. these levels will work best on htf(1day 4hr)
will work for 1 hr as well but i wont suggest using in below 1hr time frame
3. look for atleast 2 tags on a certain level.
4. as retail logic or basic ta always suggest
support turns into resistance and vice versa
i personally wont advice you to trade on breakouts
5.confluece to look out for with s/r
-trendlines, -monday range, -frvp, fibs
6.width of box would increase as you move on smaller timeframe which means that the level range is big at which we are expecting a reversal thats why i suggest to use them as confluence and not to trade.