Once you have selected your amp, you need to select an amp kit to wire it into your vehicle. This includes power and ground wire, a fuse, remote turn on wire, RCAs, speaker wire, and in some cases a few extras or a few of these components missing depending on the kit you get.
Amplifier installation kits, or wiring kits, usually include all or most of the things you need to install your amp, but you don’t need the full kit if you already have most of what you need; you can go buy whatever you’re missing separately. If starting from nothing, it’s usually a lot cheaper to get a kit. Also make sure the kit you buy includes what you need. For example: most kits only come with one set of RCAs. This is fine for a sub installation, but you will need another pair if you plan on doing 4 speakers on a 4 channel amp.
What’s in the kit?

Amp kits will include the wires, cables, fuse holders, and connectors you need to install your amp. Some include more pieces than others. This 4 gauge Rockford Fosgate amp kit (check price on Amazon) includes everything you need to get your system hooked up and sounding good. Cheaper kits can be had, but the wires won’t be true AWG size, will most likely be copper clad aluminum (CCA), won’t carry current as well as good, name brand pure copper kits, and will have cheap RCAs.