Aviation refers to the activity of flying aircraft within Earth's atmosphere. Things like the airplanes and helicopters we ride fall into this category, mainly using aerodynamics to lift off, which is different from going into outer space.

According to authoritative sources like Baidu Encyclopedia, seasonality refers to the regular fluctuations or cyclical changes that things show as the seasons change. This phenomenon is widely seen in nature, the economy, health, and data statistics.

Measuring possibility (that is, probability) is a core concept in math, statistics, and decision science, mainly using probability theory to turn uncertainty into a number between 0 and 1.

Addition is a basic operation in arithmetic, referring to the process of combining two or more numbers or amounts, represented by the plus sign '+', with the result shown using the equals sign '=', and it follows basic properties like the commutative and associative laws.

A radian is a unit for measuring angles. Simply put, it measures the size of an angle using the ratio of the arc length to the radius, and its symbol is rad. When the arc length of a circle exactly equals its radius, the central angle corresponding to that arc is 1 radian, which is roughly 57.3 degrees.

Encryption is basically just putting a lock on information, turning readable text into gibberish, and only people with a specific 'key' can restore it.

Simplifying is the process of turning complex mathematical expressions into simpler forms, mainly used in subjects like math, physics, and chemistry.

Math checking usually refers to hypothesis testing in statistics, and it also includes checking your work when doing problems and methods for verifying mathematical conclusions.

Chemistry is a basic natural science that studies the composition, structure, properties, and changes of matter at the level of molecules and atoms. It not only explains what the world is made of but also aims to create new substances to meet human needs.

Subtraction is one of the four basic arithmetic operations. The operation of taking one number away from another is called subtraction; if you know the sum of two numbers and one of the numbers, finding the other number is also called subtraction. The symbol for subtraction is '-', and it's read as 'minus'.