It's tea that's roasted over heat for an extended period of time. This process forces water out of the cells to create drier tea (which is better for storage) or even enhances the color and flavor. One reason the tea becomes darker is via the Maillard reaction, a form of nonenzymatic browning.
Tea always has caffeine, but not as much as coffee. So, yes to your question.
In its essence, coffee is a kind of tea, brewed with cherry seeds from the coffea arabica or coffea robusta plant instead of leaves of the camellia sinensis (tea) plant, and for the most part, in the processing stages for both coffee beans and tea leaves, both are dried and fermented to a certain degree, and with the exception of green tea (the exception is hōjicha, a roasted green tea) and white tea, coffee beans and many varieties of tea are roasted.
There are a few differences of the processing of coffee beans to tea leaves. They would include the coffee beans are roasted and tea leaves are withered and rolled.
Most Korean tea is green tea, which can be classified as Daejak, Jungjak, and Sejak. Korea also produces a small amount of black tea. Korea also produces herbal teas, including a drink made of roasted barley, called boricha.
Tea bags can go stale even in a container. They can even go stale on the store shelf like mine did. Look for expiry dates (the Tetley box I bought didn't have one) and get the freshest you can. Stale tea will brew a proper looking tea but it will taste like, well, sort of dusty and not at all like tea.
Roasted penuts are roasted
Ground, dried, roasted coffee beans and water, preferably hot. Also Sugar.
Durad is a type of fish. Roasted durad would be roasted fish of this type.
All types of garlic can be roasted
a roasted apple
There are many recipes which include roasted garlic. One can add roasted garlic to many Italian dishes including spaghetti sauce and lasagna. Chicken is great with roasted potatoes, seasoned with roasted garlic. Roasted garlic mashed potatoes are a popular side dish.
I think the more appropriate question is, "What can't be roasted?"