A - F

acts_as_authenticated Plugin
acts_as_authenticated is plugin for Ruby on Rails to add authenticated users to your application.

Algorithm
An algorithm is a sequence of operations to perform a certain task.

Apt-get
The apt-get command is used to install .deb software packages on Debian-based Linux distributions.

Argument
An argument to a method is a named variable in the method's definition, or an object passed to a method when called.

Array
An ordered collection of values, often assigned to a variable. In Ruby, the array takes the place of all ordered collections. They act as arrays, lists, stacks, queues, etc.

Assertion
The testing of a condition and raising an exception if the condition is not met.

assert_equal
The base assertion in the Test::Unit library. assert_equal will not fail as long as its two arguments are equal.

Associative Array
A named collection of key/value pairs.

Behavior Driven Development
A refinement of Test-Driven Development that utilizes a domain specific language to facilitate better communication between developers and clients.

Benchmark
An evaluation of how fast computer software will run.

Blacklist Filter
Any filter that describes what is not allowed.

Boolean Expression
A boolean expression is an expression that evaluates to either true or false.

Callback
Any way of informing a program of a condition.

Code Coverage
The percentage of code covered by tests.

Cookie
Simple variables stored by a website on your computer.

Cross Site Scripting (XSS)
Injecting malicious HTML tags into a website.

Cross-Site Request Forgery (CSRF)
Exploitation of a website utilizing the trust the site has for a certain user.

CRUD
An acronym for Create, Read, Update and Delete, the four primary database actions.

CsrfKiller Plugin
A Ruby on Rails plugin that implements hidden ID fields in forms as a countermeasure for Cross-site Request Forgery (CSRF) vulnerabilities.

Data Structure
A data structure is a scheme for storing related data in memory so it can be retrieved in the least amount of time.

Declare
The word "declare" is often used to refer to the creation of a variable or a method.

Define
The word "define" is used to describe how and when variables, classes and methods are first available for use.

Domain-Specific Language
The use of problem-space terminology in the solution space.

Encapsulation
Encapsulation refers to a principal in Object Oriented programming of one part of the program not being able to effect another.

Escape Sequence
The definition of 'escape sequence' as it relates to the parsing of Ruby string literals.

DRY (Don't Repeat Yourself)
You'll often hear DRY used as an adjective, such as "Is this code DRY enough?" It means Don't Repeat Yourself and seeks to avoid duplication of efforts in your code.

Forgery Protection
Any countermeasure in place to protect against Cross-site Request Forgery (CSRF) vulnerabilities or any other trust-exploiting vulnerability.