A snare can be thought of as the opposite of a speed boost. Snares can be stacked, but movement rate is capped at -50% slower than normal; however, a single skill that causes more than -50% slower movement can override the -50% cap, such as Winter's Embrace.
Body blocking. A team can heavily restrict or sometimes entirely stop an enemy movement by using their own characters' bodies as a living wall. Spirits, pets, minions, and other NPCs, such as Footmen, can help body block an enemy character.
The crippledcondition. Conditions are easily and cheaply removed, but they are also relatively easy and cheap to inflict. It is possible to stack conditions on top of the cripple to make it somewhat more difficult to remove; for example many Cripshot Rangers stack poison from Apply Poison on top of the cripple caused by Crippling Shot.
Hexes that slow. The water attribute of the elementalist, the illusion attribute of the mesmer, and the deadly arts attribute of the assassin contain many useful movement speed reducing hexes. Hexes are somewhat more difficult to remove than conditions, easier to cover to prevent removal, and tend to have more dramatic effects than the cripple condition.
Knock downs. Knock downs utterly stop an enemy target's movement and most actions for a short period of time. Knock downs last two seconds (unless otherwise noted), but the effect can be augmented by the Earthbind spirit, the Stonefist Insignia, rapid casting of knock downs with short recharges (such as Gale), or coordinated chaining of knock downs from multiple teammates.
Incentives. A few unusual spells create incentives for a target to choose to restrict his own movement, for example the Assassin's Enduring Toxin and the Necromancer's Weaken Knees hexes. In addition, there are battlefield conditions created by various skills (such as wells, wards, nukes, traps and spirits) that can convince an enemy to avoid moving into a particular area.
Because many hexes can snare, Holy Veil cast before the hexes hit in important situations allows instant removal of a snare hex.
Condition removal is good against melee heavy teams for quickly removing cripple. Mending Touch is often used.
Stances can be used for several different reasons such as providing speed boosts, blocking attacks in order to avoid cripple, and preventing knock downs.
Speed boosts themselves are a counter to at least some of the effects of snares. The balance between speed loss and gain will reduce the snare's effect; however, be careful of using enchantment based speed boosts when facing snares such as Icy Shackles.