Total Dissolved Solids (often abbreviated TDS) is a measure of the combined content of all inorganic and organic substances contained in a liquid in: molecular, ionized or micro-granular suspended form. Generally the operational definition is that the solids must be small enough to survive filtration through a sieve the size of two micrometer. Total dissolved solids are normally discussed only for freshwater systems, as salinity comprises some of the ions constituting the definition of TDS.
TDS is an important measure in coffee brewing since it determines the coffee strength, and concentration. The higher the TDS, the more body the coffee has, and the stronger it is.
Coffee brewing methods have specific TDS, hence taste differently. Turkish coffee has the highest amount of total dissolved solids, espresso is following closely. French press also has a high TDS. Drip coffee is on the lower range of TDS, and cold brew has the lowest TDS.