What It Represents
A support line connects levels where the price has stopped falling on multiple occasions in the past. Because buy orders are thought to have tended to come in around that level, some expect buying to come in again in a similar way when the price approaches it once more.
How to Read It, and What to Watch Out For
A support line is only a guideline drawn from past price movement — it does not guarantee that the price will bounce at that level. Changes in market conditions or supply and demand can cause the price to break below the line and keep falling, so it should be used only as a reference alongside other information.