Tooltip

A tooltip is the small box of text that appears when you rest the pointer over something. It tells you what the thing is. The first line is the thing's name, in white, and the lines under it say more, such as what a spell does or what an item can do.

The box follows the pointer and stands above and to the left of it. At the top or left edge of the screen, it moves to the other side so that it stays whole. A very long text is cut off with "..." at the end of the last line that fits.

Tooltip, buff — The tooltip of a buff in the buff list. It shows the buff's name, Evil Omen, and a sentence under it that says what the buff does, wrapped over several lines.

Tooltip, firstrun-choice — The tooltip of one choice in the prompt that a new character sees on first entering the game. It names the choice, Use the Classic Client's default settings, and tells what the choice does and what stays as it was.

Tooltip, item — The tooltip of an item in an open backpack, here a composite bow. It lists the item's properties, one to a line, from its name to its weight.

Tooltip, spell — The tooltip of a spell in a spellbook, here Arch Protection. It shows the spell's name, what it does, and the reagents that it uses, one to a line.

Tooltip, stock-command — The tooltip of a button on the client's own menu bar. It shows only the button's name, here Virtues.

Opening it

The tooltip appears when you rest the pointer over something that has a tooltip, such as a buff, a spell, an item, a hotbar slot or a button.
An item's tooltip appears once the server has sent the item's properties. Until then, nothing shows.
The tooltip goes away as soon as the pointer leaves the thing, or when the thing closes.

Using it

Rest the pointer over a thing to read its tooltip. Nothing needs a click.
Move the pointer, and the tooltip moves with it.
Hover over a row whose name is cut off to read the name whole.