Waders are waterproof pants and boots. They come in hundreds of different styles, colors, lining. They all do the same thing. Keep you dry, and warm. 

     Are they a necessity? Probably not. It all depends on where and when you're going. If you're just fishing from the bank, you probably won't need waders. But I would still recommend waterproof boots. Having wet feet is horrible. Cold and wet feet is even worse. Use good judgment. 

    Depending on where you are they might make a huge difference in your attitude. Nobody wants to do much if they're miserable. Most of fishing is mental. But if your cozy and warm standing in that stream, it kind be a very peaceful place.

Keep sound wisdom and discretion Proverbs 3:21