|200 DMA means 200-day moving average. It's the average price of an asset over the last 200 days. A chart of the price vs. the 200 dma conveys information from the unscientific field of Technical Analysis. It is considered a support or resistance barrier. When the price is above the 200 dma it's considered bullish and when below the 200 dma considered bearish.|
A 200 DMA can't be calculated until you have 200 prices.
Many charting software has the ability to add a 200 DMA line to the chart.
Example to calculate a 200 DMA.
Example with random data