Placidus
Placidus is a time-based house system that divides the hours it takes a degree to rise from the horizon to the meridian, and it is the most widely used system in modern Western astrology.
Its houses are unequal, and deliberately so: the division follows the actual rate at which degrees climb, which varies with latitude and season. That is also its weakness, because inside the polar circles some degrees never rise and the system breaks down.
Every written interpretation on this site uses Placidus. That is a choice rather than a verdict, and its value is consistency: a reading that mixed systems would be describing two different charts.
Frequently asked
Why is Placidus the default almost everywhere?
Largely history. It spread through printed tables in the eighteenth and nineteenth centuries and became the assumption software inherited.
Is Placidus the correct house system?
There is no settled answer. What matters more is not mixing systems inside one reading, which is why ours uses it throughout.