The Magneboots was a gadget found in the first game that allows Ratchet to walk up specific magnetic surfaces. These are usually ventilation shafts, but they can also be the undersides of spacecraft and certain platforms that transport you to other areas.
The Magneboots were invented by the Blarg, and Clank found a pair whilst exploring the surfaces of the now-abandoned planet of Orxon, where the boots were one of the things left behind (amongst others such as Infobots and Health Upgrades). The Magneboots are required for Ratchet to continue and explore many areas in the worlds he visits. However, because all of the weapons and gadgets Ratchets uses are made from magnetic metal, he is only able to use the Wrench whilst using the Magneboots (this is explained because the Wrench also has a magnet that attracts bolts, and the animation of Ratchet swinging his Wrench is higher than normal, due to the magnetic field of the boots).
Ratchet is also unable to jump as a result of the magnets, however he can attempt to if the player presses X, the usual command for jump. The Magnetboots are considered vastly inferior to Megacorp's and Vox Industries' Gravity Boots.