Lossless Compression: a data compression algorithm that allows the original data to be perfectly reconstructed from the compressed data.
Lossy Compression: (or irreversible compression) a data compression method that uses inexact approximations, discarding some data to represent the content. Most commonly seen in image formats like .jpg.
Aggregation: a computation in which rows from a data set are grouped together and used to compute a single value of more significant meaning or measurement. Common aggregations include: Average, Count, Sum, Max, Median, etc.
Pivot Table: in most spreadsheet software it is the name of the tool used to create summary tables.
Summary Table: a table that shows the results of aggregations performed on data from a larger data set, hence a "summary" of larger data. Spreadsheet software typically calls them "pivot tables".
For Loop: A particular kind of looping construct provided in many languages. Typically, a for loop defines a counting variable that is checked and incremented on each iteration in order to loop a specific number of times.
Loop: The action of doing something over and over again.
asymmetric encryption: used in public key encryption, it is scheme in which the key to encrypt data is different from the key to decrypt.
modulo: a mathematical operation that returns the remainder after integer division. Example: 7 MOD 4 = 3
Private Key: In an asymmetric encryption scheme the decryption key is kept private and never shared, so only the intended recipient has the ability to decrypt a message that has been encrypted with a public key.
Public Key Encryption: Used prevalently on the web, it allows for secure messages to be sent between parties without having to agree on, or share, a secret key. It uses an asymmetric encryption scheme in which the encryption key is made public, but the decryption key is kept private.
Data Type: All values in a programming language have a "type" - such as a Number, Boolean, or String - that dictates how the computer will interpret it. For example 7+5 is interpreted differently from "7"+"5"
Expression: Any valid unit of code that resolves to a value.
Variable: A placeholder for a piece of information that can change.
==: The equality operator (sometimes read: "equal equal") is used to compare two values, and returns a Boolean (true/false). Avoid confusion with the assignment operator "=",
Global Variable: A variable whose scope is "global" to the program, it can be used and updated by any part of the code. Its global scope is typically derived from the variable being declared (created) outside of any function, object, or method.
If-Statement: The common programming structure that implements "conditional statements".
Local Variable: A variable with local scope is one that can only be seen, used and updated by code within the same scope. Typically this means the variable was declared (created) inside a function -- includes function parameter variables.
Variable Scope: dictates what portions of the code can "see" or use a variable, typically derived from where the variable was first created. (See Global v. Local)
Models and Simulations: a program which replicates or mimics key features of a real world event in order to investigate its behavior without the cost, time, or danger of running an experiment in real life.
for loop: A typical looping construct designed to make it easy to repeat a section of code using a counter variable. The for loop combines the creation of a variable, a boolean looping condition, and an update to the variable in one statement.
Return Value: A value sent back by a function to the place in the code where the function was called form - typically asking for value (e.g. getText(id)) or the result of a calculation or computation of some kind. Most programming languages have many built-in functions that return values, but you can also write your own.