Machine learning
Machine learning (ML) is / the scientific study / of algorithms and statistical models / that computer systems use to / effectively perform a specific task / without using explicit instructions, relying on patterns and inference(推理) instead. （是什么）
Machine learning algorithms build a mathematical model of sample data, known as "training data", in order to / make predictions or decisions / without being explicitly programmed to perform the task. （如何构建起来的）
Machine learning is closely related to computational（计算的） statistics, / which focuses on making predictions using computers. In its application across business problems(跨界问题), machine learning is also referred to as predictive analytics.（作用是什么）
机器学习（ML）是对算法和统计模型的科学研究，计算机系统用于有效地执行特定任务，而不使用明确的指令，而是依赖模式和推理（推进）。（认证） 机器学习算法建立一个样本数据的数学模型，称为“训练数据”，以便/做出预测或决策/而不需要明确编程来执行任务。（如何构造起的） 机器学习与计算的统计密切相关，/这集中于使用计算机进行预测。在跨行业问题的应用中，机器学习也被称为预测分析。
Object-oriented programming
Object-oriented programming (OOP) is a programming / based on the concept of "objects", which can contain data and functions. It can use the object to call the methods and complete the operations. （对象是什么，作用）
In OOP, computer programs are designed by making them out of objects / that interact with one another. OOP languages are class-based, meaning that objects are instances of classes, which also determine their types.（基于类，对象是类的实例）
面向对象编程（OOP）是一种基于“对象”概念的编程，它可以包含数据和函数。它可以使用对象调用方法并完成操作。 在面向对象编程（OOP）中，计算机程序是通过使它们脱离对象/相互作用而设计的。OOP语言是基于类的，这意味着对象是类的实例，这也决定了它们的类型。
Cache
In computing, a cache is a hardware or software component that stores data so that future requests for that data can be served faster; the data stored in a cache might be the result of an earlier computation or a copy of data stored elsewhere. （Cache如何产生）
A cache hit occurs when the requested data can be found in a cache, while a cache miss occurs when it cannot. Cache hits are served by reading data from the cache, which is faster than recomputing a result or reading from a slower data store; thus, the more requests that can be served from the cache, the faster the system performs.（命中对速度的影响）
在计算中，缓存是一种硬件或软件组件，用于存储数据，以便能够更快地为将来对该数据的请求提供服务；存储在缓存中的数据可能是早期计算或存储在其他位置的数据副本的结果。 当请求的数据可以在缓存中找到时，会发生缓存命中；当无法找到时，会发生缓存未命中。缓存命中通过从缓存中读取数据提供服务，这比重新计算结果或从较慢的数据存储中读取更快；因此，可以从缓存中提供的请求越多，系统执行得越快。
Big data
Big data is a field that treats of ways to analyze, systematically extract information from, or otherwise deal with data sets。
Big data was originally associated with three key concepts: volume, variety, and velocity. Other concepts later attributed with big data are veracity ( how much noise is in the data) and value.
Current usage of the term big data tends to refer to the use of predictive analytics, user behavior analytics, or certain other advanced data analytics methods that extract value from data, and seldom to a particular size of data set.
大数据是一个研究如何分析、系统地从数据集中提取信息或以其他方式处理数据集的领域。 大数据最初与三个关键概念联系在一起：体积、多样性和速度。后来被认为是大数据的其他概念是准确性（数据中有多少噪声）和价值。 “大数据”一词的当前用法倾向于指使用预测分析、用户行为分析或某些其他高级数据分析方法，这些方法从数据中提取价值，很少使用特定大小的数据集。
Cloud computing
Cloud computing is the on demand availability of computer system resources, especially data storage and computing power, without direct active management by the user. The term is generally used to describe data centers available to many users over the Internet.
Large clouds, predominant today, often have functions distributed over multiple locations from central servers. If the connection to the user is relatively close, it may be designated an edge server.
Cloud computing relies on sharing of resources to achieve coherence and economies of scale.
云计算是指计算机系统资源，特别是数据存储和计算能力的按需可用性，用户没有直接的主动管理。该术语通常用于描述许多用户可通过互联网使用的数据中心。 如今占主导地位的大型云通常具有从中央服务器分布到多个位置的功能。如果与用户的连接相对较近，则可以将其指定为边缘服务器。 云计算依靠资源共享来实现一致性和规模经济。
Internet of things
The Internet of things (IoT) refers to the concept of extending Internet connectivity beyond conventional computing platforms such as personal computers and mobile devices, and into any range of traditionally "dumb" or non-internet-enabled physical devices and everyday objects.
Embedded with electronics, Internet connectivity, and other forms of hardware (such as sensors), these devices can communicate and interact with others over the Internet, and they can be remotely monitored and controlled.
物联网（IOT）是指将互联网连接扩展到传统计算平台（如个人计算机和移动设备）之外，并扩展到任何传统的“哑”或非互联网物理设备和日常物品的概念。
这些设备嵌入电子设备、互联网连接和其他形式的硬件（如传感器），可以通过互联网与其他设备进行通信和交互，并且可以远程监控。
计算机视觉、计算机图形学、图像处理的区别和联系
计算机视觉(CV)：
Computer vision is a field that includes methods for acquiring, processing, analyzing, and understanding images and, in general, high-dimensional data from the real world in order to produce numerical or symbolic information, e.g., in the forms of decisions.
计算机视觉是一个学科/领域，它包括获取、处理、分析和理解图像或者更一般意义的真实世界的高维数据的方法；它的目的是产生决策形式的数字或者符号信息。
对于视觉算法来说，大致可以分为以下5个步骤：特征感知，图像预处理，特征提取，特征筛选，推理预测与识别。
1981年诺贝尔医学生理学奖颁发给了David Hubel，一位神经生物学家。他的主要研究成果是发现了视觉系统信息处理机制，证明大脑的可视皮层是分级的。他的贡献主要有两个，一是他认为人的视觉功能一个是抽象，一个是迭代。抽象就是把非常具体的形象的元素，即原始的光线像素等信息，抽象出来形成有意义的概念。这些有意义的概念又会往上迭代，变成更加抽象，人可以感知到的抽象概念。
像素是没有抽象意义的，但人脑可以把这些像素连接成边缘，边缘相对像素来说就变成了比较抽象的概念；边缘进而形成球形，球形然后到气球，又是一个抽象的过程，大脑最终就知道看到的是一个气球。
如果要完全模拟人脑，我们也要模拟抽象和递归迭代的过程，把信息从最细琐的像素级别，抽象到“种类”的概念，让人能够接受。
计算机图像学(CG)：
Computer graphics is a sub-field of computer science which studies methods for digitally synthesizing and manipulating visual content. Although the term often refers to the study of three-dimensional computer graphics, it also encompasses two-dimensional graphics and image processing.
计算机图形学是计算机科学的一个子领域，它包括数字合成和操作可视内容（图像、视频）的方法。尽管这个术语通常指三维计算机图形学的研究，但它也包括二维图形学和图像处理。
图像处理（IP）：
In imaging science, image processing is processing of images using mathematical operations by using any form of signal processing for which the input is an image, such as a photograph or video frame; the output of image processing may be either an image or a set of characteristics or parameters related to the image.
在图像科学中，图像处理是用任何处理信号等数学操作 处理图像的过程，输入时图像（摄影图像或者视频帧），输出是仍然是图像或者与输入图像有关的特征、参数的集合。
区别与联系：
Computer Graphics和Computer Vision是同一过程的两个方向。 Computer Graphics将抽象的语义信息转化成图像； Computer Vision从图像中提取抽象的语义信息。 Image Processing探索的是从一个图像或者一组图像之间的互相转化和关系，与语义信息无关。
从输入输出角度看：
区别：
Computer Graphics，简称 CG 。输入的是对虚拟场景的描述，通常为多边形数组，而每个多边形由三个顶点组成，每个顶点包括三维坐标、贴图坐标、rgb 颜色等。输出的是图像，即二维像素数组。
Computer Vision，简称 CV。输入的是图像或图像序列，通常来自相机、摄像头或视频文件。输出的是对于图像序列对应的真实世界的理解，比如检测人脸、识别车牌。
Digital Image Processing，简称 DIP。输入的是图像，输出的也是图像。Photoshop 中对一副图像应用滤镜就是典型的一种图像处理。常见操作有模糊、灰度化、增强对比度等。
联系：
CG 中也会用到 DIP，现今的三维游戏为了增加表现力都会叠加全屏的后期特效，原理就是 DIP，只是将计算量放在了显卡端。
CV 更是大量依赖 DIP 来打杂活，比如对需要识别的照片进行预处理。
最后还要提到近年来的热点——增强现实（AR），它既需要 CG，又需要 CV，当然也不会漏掉 DIP。它用 DIP 进行预处理，用 CV 进行跟踪物体的识别与姿态获取，用 CG 进行虚拟三维物体的叠加。
Augmented reality (AR)
Augmented reality (AR) is an interactive experience of a real-world environment where the objects that reside in the real-world are "augmented" by computer-generated perceptual information, sometimes across multiple sensory modalities, including visual, auditory, haptic, somatosensory, and olfactory.
The overlaid sensory information can be constructive (i.e. additive to the natural environment) or destructive (i.e. masking of the natural environment) and is seamlessly interwoven with the physical world such that it is perceived as an immersive aspect of the real environment.
In this way, augmented reality alters one's ongoing perception of a real-world environment, whereas virtual reality completely replaces the user's real-world environment with a simulated one.
增强现实（AR）是现实环境中的一种互动体验，在这种环境中，居住在现实世界中的物体被计算机生成的感知信息“增强”，有时跨越多种感官模式，包括视觉、听觉、触觉、体感和嗅觉。
重叠的感官信息可以是构造性（即对自然环境的附加）或破坏性（即对自然环境的遮蔽），并与物理世界无缝地交织在一起，使其被视为真实环境的一个沉浸式方面。现实完全用一个模拟的环境来代替用户的现实环境。
The 7 Layers of the OSI
Application (Layer 7) OSI Model, Layer 7, supports application and end-user processes. Communication partners are identified, quality of service is identified, user authentication and privacy are considered, and any constraints on data syntax are identified. Everything at this layer is application-specific. This layer provides application services for file transfers, e-mail, and other network software services. Telnet and FTP are applications that exist entirely in the application level. Tiered application architectures are part of this layer.
Layer 7 Application examples include WWW browsers, NFS, SNMP, Telnet, HTTP, FTP
OSI模型，第7层，支持应用程序和最终用户进程。识别通信伙伴，识别服务质量，考虑用户身份验证和隐私，识别数据语法上的任何约束。这一层的所有内容都是特定于应用程序的。此层为文件传输、电子邮件和其他网络软件服务提供应用程序服务。telnet和ftp是完全存在于应用程序级别的应用程序。分层应用程序体系结构是这一层的一部分。
Presentation (Layer 6) This layer provides independence from differences in data representation (e.g., encryption) by translating from application to network format, and vice versa. The presentation layer works to transform data into the form that the application layer can accept. This layer formats and encrypts data to be sent across a network, providing freedom from compatibility problems. It is sometimes called the syntax layer.
Layer 6 Presentation examples include encryption, ASCII, EBCDIC, TIFF, GIF, PICT, JPEG, MPEG, MIDI.
通过从应用程序转换为网络格式，该层提供了独立于数据表示（如加密）差异的功能，反之亦然。表示层的工作是将数据转换成应用层可以接受的形式。这一层对要通过网络发送的数据进行格式化和加密，从而避免了兼容性问题。它有时被称为语法层。
Session (Layer 5) This layer establishes, manages and terminates connections between applications. The session layer sets up, coordinates, and terminates conversations, exchanges, and dialogues between the applications at each end. It deals with session and connection coordination.
Layer 5 Session examples include NFS, NetBios names, RPC, SQL.
该层建立、管理和终止应用程序之间的连接。会话层设置、协调和终止每端应用程序之间的对话、交换和对话。它处理会话和连接协调。
Transport (Layer 4) OSI Model, Layer 4, provides transparent transfer of data between end systems, or hosts, and is responsible for end-to-end error recovery and flow control. It ensures complete data transfer.
Layer 4 Transport examples include SPX, TCP, UDP.
OSI模型，第4层，在终端系统或主机之间提供透明的数据传输，并负责端到端错误恢复和流控制。它确保了完整的数据传输。
Network (Layer 3) Layer 3 provides switching and routing technologies, creating logical paths, known as virtual circuits, for transmitting data from node to node. Routing and forwarding are functions of this layer, as well as addressing, internetworking, error handling, congestion control and packet sequencing.
Layer 3 Network examples include AppleTalk DDP, IP, IPX.
第3层提供交换和路由技术，创建逻辑路径，称为虚拟电路，用于将数据从节点传输到节点。路由和转发是这一层的功能，也是寻址、互联、错误处理、拥塞控制和包排序的功能。
Data Link (Layer 2) At OSI Model, Layer 2, data packets are encoded and decoded into bits. It furnishes transmission protocol knowledge and management and handles errors in the physical layer, flow control and frame synchronization. The data link layer is divided into two sub layers: The Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. The MAC sub layer controls how a computer on the network gains access to the data and permission to transmit it. The LLC layer controls frame synchronization, flow control and error checking.
Layer 2 Data Link examples include PPP, FDDI, ATM, IEEE 802.5/ 802.2, IEEE 802.3/802.2, HDLC, Frame Relay.
在OSI模型第2层，数据包被编码并解码成比特。它提供传输协议知识和管理，并处理物理层、流控制和帧同步中的错误。数据链路层分为两个子层：媒体访问控制（MAC）层和逻辑链路控制（LLC）层。MAC子层控制网络上的计算机如何访问数据并获得传输数据的权限。LLC层控制帧同步、流控制和错误检查。
Physical (Layer 1) OSI Model, Layer 1 conveys the bit stream - electrical impulse, light or radio signal — through the network at the electrical and mechanical level. It provides the hardware means of sending and receiving data on a carrier, including defining cables, cards and physical aspects. Fast Ethernet, RS232, and ATM are protocols with physical layer components.
Layer 1 Physical examples include Ethernet, FDDI, B8ZS, V.35, V.24, RJ45.
OSI模型，第1层通过网络在电气和机械层面传输位流——电脉冲、光或无线电信号。它提供在载体上发送和接收数据的硬件手段，包括定义电缆、卡和物理方面。快速以太网、RS232和ATM是带有物理层组件的协议。