Ignite is a verb that means to start heat or a flame. Trying to ignite a match inside a dark fireworks factory is a really bad idea — one that can get you blown sky high.
The literal definition of ignite is to cause something to catch fire or burn. Dousing a house in gasoline and putting a lit match to the front door will surely cause the home to ignite. In its more figurative sense, ignite means to inspire intense feelings. A passionate kiss can ignite a fiery romance, but if one of the people doing the kissing is married to someone else, that kiss could ignite a spouse's fury.