An Environmental suit or EV suit is a specialised type of clothing used to project the wearer from hazards and maintain life-support in inhospitable environments.
EV suits can be used for a variety of tasks; for extravehicular activities, to explore a non-class M environments (or dependent on your species whatever environments might usually cause you harm) or to work in hazardous areas protected from various forms of chemicals and radiations.
There are a number of specialised EV suits, with magnetic boots to walk on the hull of a starship or a small propulsion unit to allow independent travel a short distance into open space. Anthropological isolation suits seem to stem from EV suit technologies sealing a researcher off from their unsuspecting study subjects.
History of EV suits
An away team from the Enterprise NX-01 using EV suits to explore the interior of an alien ship (The Crossing)
22nd century
EV suits used by Earth Starfleet in the 22nd century were a bronze colour utilising a soft body suit with more solid components where necessary. These EV suits had magnetic boots and had various safety measures such as the ability to share an oxygen supply if one users was damaged or lost.
The suits were generally emblazoned with the mission patch of the starship they were assigned to and key crew members had there own tailored suits whilst over personal utilised shared suits. MACOs also had there own style of suit presumably designed to be more effective in combat situations.
(Enterprise episodes: Babel One, The Catwalk, The Crossing and Minefield)
A rescue party from the USS Enterprise using EV suits in a Ngultor ship (Flesh of my Flesh)
23rd century
By the 2250s Federation Starfleet used an orange EV suit with more generally more flexible components than there 22nd century predecessors.
A later 23rd century EV suit (The Tholian Web)
By the 2260s Starfleet began to use new Silver suits which consisted of mostly of a flexible form fitting body suit with a tall helmet. Later in the decade Starfleet began to use life support belts, a type of personal force field, however these seemed to have been phased out in later years as Starfleet returned to more solid suit designs.
Tom Paris and B'Elanna Torres in EV suits in open space (Day of Honor)
24th century
By the 24th century Starfleet was using a white EV suit with a body suit and solid components which were of form fitting design to fit the user to without restrictions of movement and vision.
External Link
Environmental suit article at Memory Alpha, the wiki for canon Star Trek.