Glass bottles come in various shapes and size in order accommodate the packaging of your product. They are used as wine bottles, chemical bottles, food jars, pill bottles, sauce containers, spice containers, and pharmaceutical bottles.
Although glass is a bit more expensive than plastic, it does have the advantageous properties of being non-corrosive and non-reactive. It does not rust and does not degrade easily. Unlike plastic, glass maintains its shape well. Under certain conditions, plastics may leach chemical out of the plastic and into the contained product. That is why one should not microwave nor heat certain plastics; whereas nearly all glass are microwavable.
Certain product must by nature be contained in glass. Olive oil is an example; you never see that coming in plastic containers. Other products (such as vitamins) can be contained in glass or plastics. However, keep in mind that packaging your product in glass rather than plastic gives your customers the impression of quality.
Glass bottles can be optically transparent or colored. Amber and cobalt blue glass are very common and popular. Dark amber is suitable for products that are light-sensitive or heat-sensitive. Olive oils and pharmaceuticals are such examples.
It is not a problem if you need your bottle to comply with OSHA (Occupational Safety and Health Administration), DOT (Department of Transportation), and UPS. Many manufactures do have them, you just have to ask.
If you cannot find any stock glass bottles that suit your needs, there are shops that can easily custom mold one to your specification. As the required lead time varies from manufacturer to manufacture, you should ask about their time frame and allow for sufficient time by planning in advance.