Hydrochloric acid, HCl, is very strong, and helps to break down the food you eat so your body can use it. The HCl would burn your skin if you spilled it on yourself. But the stomach is lined with lots of mucus layers that protect the rest of your organs from the acid. Bases contain hydroxide ions. The more hydroxide ions, the stronger the base.
Bases make Litmus turn blue.
If you dipped red litmus paper into baking soda or bleach, the paper would turn blue. If you dipped blue litmus into either, the blue paper would stay blue. A substance that tastes bitter and feels slippery is probably a base. You should never taste strong bases. It would be fatal.