Achar refers to South Asian pickles made from ingredients such as mango, lime, chilies or mixed vegetables. Salt, spices, oil, acidity and preservation methods vary widely by region and recipe. A small portion supplies a concentrated contrast to rice, breads and other dishes.
It is not one fixed recipe and need not resemble a Western cucumber pickle. Do not infer shelf stability from its name: follow the maker's storage directions or a tested preservation recipe.
Reference: Further reading.
Related: pickle.