Vinegar is truly the wonder liquid of any kitchen or laundry. It is so versatile and one little bottle can substitute for over a hundred cleaners, softeners, flavours, baking agents. Add and soak leftover citrus peel to it for one of the most powerful scum cleaners; add baking soda to clean fruit & vegetables; add dishwashing soap to clean bathrooms.
Vinegar is an acidic liquid produced through the fermentation of ethanol by acetic acid bacteria. Most household vinegar is around 4 percent acetic acid by volume, but may be up to 8 percent (referred to as double strength). Usually, the acetic acid is produced by a double fermentation, converting simple sugars to ethanol using yeast, and ethanol to acetic acid, using acetic acid bacteria.
Because it is an acid, vinegar is self-preserving and resistant to bacterial growth and spoilage; does not need refrigeration; and will stay virtually unchanged over an extended period of time. While the appearance of vinegar will change over time, and it certainly has a 'peak', the reality is that it will last indefinitely. You might see some cloudiness over time as once opened and exposed to air, harmless “vinegar bacteria” may start to grow. Some sediment might accumulate as vinegars are usually filtered to make them clear. Those that are less filtered can form sediment over time as the particles settle.
In some cases, the 'mother' might appear. Many vinegars are pasteurized, but if not (raw);or when pasteurization is incomplete; or the vinegar is re-inoculated with vinegar bacteria from the air after opening, a slimy, amorphous blob or substance will form and float near the bottom. This is a vinegar mother and is just bacteria that feeds on alcoholic liquids. If one develops, it simply means that there were some sugars or alcohol that weren’t completely fermented in the vinegar process. Mother can be strained out using a coffee filter if you really want it gone, but it's harmless.
Vinegar is not only a versatile and safe household staple, it is also cheap. Google is alive with uses for it so it's probably best to simple google 'uses for vinegar', but one great place to start is cleaning. No kitchen or bathroom needs anything more on its shelves than liquid soap, vinegar and bicarbonate soda.