What is dma (direct market access)?

can someone plz explain this in detail about who can trade through dma or what is the cost etc…

Check this -

https://tradingqna.com/t/do-fiis-have-direct-market-access-dma-and-apart-from-that-which-institutions-have-dma-are-dealer-terminals-and-dma-the-same-thing/5902

NOT HELPFULL CAN SOMEBODY EXPLAIN WHAT RETAIL TRADER HAS TO FOR DMA (LIKE MINIMUM REQ,PAPER ETC)strong text