You need to know which egg to incubate.
One of the more exercise-focused aspects of Pokémon Go is hatching eggs. Each egg has a distance meter next to it, and when you put that egg in an incubator it becomes active. When you walk the distance marked on the egg while playing the game, the egg will hatch and you'll get a brand new Pokémon with a bunch of Pokémon Candy for that creature.
The difficult thing here isn't the walking, it's choosing which egg to incubate next. You only get one incubator with unlimited uses, and every other incubator — whether purchased or received from a level up — has a five use limit. The best way to choose which eggs go in which incubator is to know which Pokémon are in the egg to begin with. While there's no what to know exactly which creature is in your specific egg, here's a list of Pokémon and the egg types they show up in.
ID Name Distance
001 Bulbasaur 2km
004 Charmander 2km
007 Squirtle 2km
010 Caterpie 2km
013 Weedle 2km
016 Pidgey 2km
019 Rattata 2km
021 Spearow 2km
025 Pikachu 2km
035 Clefairy 2km
039 Jigglypuff 2km
041 Zubat 2km
074 Geodude 2km
129 Magikarp 2km
023 Ekans 5km
027 Sandshrew 5km
029 Nidoran♀ 5km
032 Nidoran♂ 5km
037 Vulpix 5km
043 Oddish 5km
046 Paras 5km
048 Venonat 5km
050 Diglett 5km
052 Meowth 5km
054 Psyduck 5km
056 Mankey 5km
058 Growlithe 5km
060 Poliwag 5km
063 Abra 5km
066 Machop 5km
069 Bellsprout 5km
072 Tentacool 5km
077 Ponyta 5km
079 Slowpoke 5km
081 Magnemite 5km
083 Farfetch'd 5km
084 Doduo 5km
086 Seel 5km
088 Grimer 5km
090 Shellder 5km
092 Gastly 5km
096 Drowzee 5km
098 Krabby 5km
100 5km
102 5km
104 5km
108 5km
109 5km
111 Rhyhorn 5km
114 Tangela 5km
115 Kangaskhan 5km
116 Horsea 5km
118 Goldeen 5km
120 Staryu 5km
128 Tauros 5km
137 Porygon 5km
095 Onix 10km
106 Hitmonlee 10km
107 Hitmonchan 10km
113 Chansey 10km
122 Mr. Mime 10km
123 Scyther 10km
124 Jynx 10km
125 Electabuzz 10km
126 Magmar 10km
127 Pinsir 10km
131 Lapras 10km
133 Eevee 10km
138 Omanyte 10km
140 Kabuto 10km
142 Aerodactyl 10km
143 Snorlax 10km
147 Dratini 10km