Mangrove Jack's craft brewer's yeast sold at arishtam.com is in the dry form. Dry yeast is easy to store, transport, and carry. The wet yeast on the other hand needs to be chilled at all times and has a shelf life of a few weeks (as compared to almost 2 years for dry yeast). As a result for a hobby brewer and even microbrewery dry yeast is much more convenient and easy to use.
Although most manufacturers recommend that you use the yeast directly, but rehydrating the yeast is always advisable for the following reasons:
When hydrated, the yeast forms spores and goes into inactive state. By hydrating it in a sugar/wort plus nutrient solution, you give it adequate time and jumpstart to become fully active again. Yeast often dies when expired, mishandled, exposed to humidity or high temperaures during transportation or storage. If you pinch it directly in the wort, it will take 24-48 hours before you can detect yeast inactivity. By hydrating the yeast, you are always 100% sure the yeast is active. Hydrated yeast have a jumpstart over any other contaminents or microbial infection. When the wort is cooled, it sometimes picks up infection from the fermenter or air. If the dry brewer's yeast is hydrated (good yeast count) they are able to fend off infection by the mere fact that they are more in number and faster in activity.
Process:
Take 5-10X of sterlized water (boil the wort or water) (50ml) If you are using water then add some priming sugar or table sugar to make a 5% solution (2.5gm or 1/2 teaspoon). DME or wort can be also used instead of sugar. (optional) add nutrients 1/4gm per 50ml. Boil and cool it to body temperature. Once the solution has cooled to 25-35 degrees celsius then add your yeast (5gm) Wait for 30 minutes to foaming to start and then add it to your beer wort or wine must.
If the foaming has not happened. Then wait for another 30 minutes. If not then the yeast is probably inactive and it might be best to use a backup sachet.