Exploring is a style of play in which the player attempts to accumulate as much land as possible by generating land via Exploration. The player will train enough troops to defend the attackers in range and explore as much land as can be afforded.
There are a few ways in which a player may successfully explore to a high land size. Success at exploring depends primarily on racial selection, the speed with which you explore acres, and the composition of your buildings (referred to as a player's "build").
Not every race is equally suited to exploring, but every race is capable of exploring to some degree. Only a few races are not viable to compete with as an explorer.
The most consistent exploring races are the those with a high degree of efficiency. Other, less efficient races can be played as fast explorers.
Pace of Exploration
The pace of a player's acre exploration is mostly determined by their race.
Fast, inefficient races will primarily train defensive specialist (spec DP) troops and explore more acres early in the round, since those races typically have high population bonuses and spec DP can provide a high amount of cheap defensive power early in the round, which leaves more platinum to be spent on exploration. Using a significant percentage of draftees on cheap, inefficient troops results in a more difficult late-round experience. The key to succeeding with these races is attaining an early land lead over other dominions, particularly all attackers.
Slower, efficient races may train some spec DP early, but will typically focus on defensive elite troops. The tradeoff is that they won't be able to afford to explore for as many acres as a faster race would early in the round, but later in the round their economy could be significantly better.
A player's build depends heavily on the chosen race, but most races will have some similarity in terms of needing farms, homes, ore mines, etc. Some explorers may choose not to build maximum smithies, or may choose to forgo building any at all. All explorers should attempt to have as little job opportunity cost as possible in order to maximize their income.
Fast races attempting to competitively explore may rely on building mods early and maintain them throughout the round.
Slower, efficient races will more often build investment buildings such as diamond mines, ore mines, or lumberyards and increase castle improvements, then reconstruct those buildings late in the round to mod buildings.