The SRD states:
Certain spells have a special tag: ritual. Such a spell can be cast following the normal rules for spellcasting, or the spell can be cast as a ritual. The ritual version of a spell takes 10 minutes longer to cast than normal. It also doesn’t expend a spell slot, which means the ritual version of a spell can’t be cast at a higher level. To cast a spell as a ritual, a spellcaster must have a feature that grants the ability to do so. The cleric and the druid, for example, have such a feature. The caster must also have the spell prepared or on his or her list of spells known, unless the character’s ritual feature specifies otherwise, as the wizard’s does.
Does this mean that when a spell is cast as a ritual, it is still available later? For example, augury has the ritual tag, so if a caster that has it prepared and can spare the extra 10 minutes, then they can cast it as a ritual, and then cast it again later in the day (at which point they can cast it again as a ritual, and retain the spell for later use, etc.)?