Ignition is obviously an important part because most fireworks and other devices need an ignition source. The exception to this is impact devices. There are two main kinds of ignition products, fuse and electric.

See also, Rat's ignition page here, and David's ignition section here.

There are several different types of fuses and most are used for fireworks.

Paper fuse: Pretty much useless. Used mostly for firecrackers. It is bad because it has an inconsistent burn rate (its not too bad, but still not good) it is not anywhere near durable, and is not water resistant.

Paper fuse (not a very good pic...):

Blackmatch: Blackmatch is generally homemade and used like safety fuse when you want easily ignited fuse and don't need super consistent burn rate. It is obviously black in color, and thicker than paper fuse. The picture below is commercial blackmatch and looks a bit like darker and thicker paper fuse. Homemade blackmatch is generally thicker than this pic and more lumpy.

Blackmatch:

Quickmatch (aka piped match): Quickmatch is blackmatch wrapped in a paper casing, making it burn almost instantly. This is used for ignited multiple fuses at the same time and is used for aerial shells along with a leader fuse of visco.

Quickmatch:

Safety fuse (aka visco, cannon fuse, green fuse): The most useful kind of fuse. This is used for delay on most fireworks and other devices. It is the only kind I use except for electrical ignition. Safety fuse is durable, has a very consistent burn rate, and can burn under water (as long as it is coated fuse). There are many sizes of safety fuse, and also different colors. The different colors either mean different burn speed, or less side spit. You can buy safety fuse from many places, some of the best are in the supplier's section. Another good source of fuse if you cannot order it, is from fireworks. If you use bottle rockets for powder you will have tons of fuse that can be taped together for longer delays. If you hook the two ends together and tape it, it is very reliable. I have done tests of 30 bottle rocket fuses taped together and got a time of 1:52 (min:sec) with no problem. The only downside is underwater one fuse will not reliably ignite another taped to it. Crackling balls have good fuse for another source, and aerial shell fuse can be used but it burns pretty fast and is usually not coated so it won't work underwater.

Safety fuse:

Time fuse: Extra fancy and expensive, this stuff is used for shells because it has no side spit to ignite powder prematurely. It is used for precise timing, hence the name time fuse. You can get it from the people in the supplies section.

Time fuse taken from a shell:

Electrical ignition: Electrical ignition is nice because you can know and control exactly when it goes off. There are a lot of professional types, but being the bum that I am, I use the igniters from estes rockets. They are kind of fragile, so I insulate the two leads and twist them together into one strand so they don't break as easily. You can also make your own or buy them. I don't use electrical much because it makes things more a lot more complicated.

Click here for more info on the topic of ignition (different website).