Puzzle 5: Save the prisoners

There are 100 prisoners. The warden will make them stand in a queue and put black or white hats on each of them. Each prisoner can see the color of the hats of prisoners ahead of them only, and not theirs or the ones behind. If any prisoner can correctly say the color of their hat, he/she will be freed, else hanged. They can guess in any order. The prisoners talk beforehand to come up with a strategy to save the most prisoners possible. What is the most number of prisoners they can save?