尽可能简单地说，套接字和端口之间没有物理区别，例如PATA和SATA之间的区别。它们只是一些读写网卡的软件。

A port is essentially a public socket, some of which are well-known/well-accepted, the usual example being 80, dedicated to HTTP. Anyone who wants to exchange traffic using a certain protocol, HTTP in this instance, canonically goes to port 80. Of course, 80 is not physically dedicated to HTTP (it's not physically anything, it's just a number, a logical value), and could be used on some particular machine for some other protocol ad libitum, as long as those attempting to connect know which protocol (which could be quite private) to use.

套接字本质上是一个私有端口，为连接方知道但其他人不一定知道的特定目的而建立。底层传输层通常是TCP或UDP，但也不一定非得如此。最基本的特征是两端都知道发生了什么，不管发生了什么。

这里的关键是，当在某个端口上接收到连接请求时，应答握手包括有关为服务特定请求者而创建的套接字的信息。后续通信通过该(私有)套接字连接进行，而不是服务继续侦听连接请求的公共端口连接。

套接字是一种数据I/O机制。端口是通信协议的契约概念。套接字可以没有端口而存在。一个端口可以没有特定的套接字而存在(例如，如果同一个端口上有几个活动的套接字，这可能是某些协议允许的)。

端口用于确定接收端应该将数据包路由到哪个套接字，在许多协议中，但它并不总是必需的，接收套接字的选择可以通过其他方式完成——端口完全是网络子系统中协议处理程序使用的工具。例如，如果协议不使用端口，数据包可以到所有侦听套接字或任何套接字。

I know that there are lot of explanations. But, there is one more easy way to understand with practical example. We all can connect to HTTP port 80, but does it mean only one user can connect to that port at a time?. The answer is obviously 'no'. Multiple users for multiple purposes can access HTTP port 80 but they still get proper response they are waiting for, from the server, can't they?. Now think about it for a minute, how?. Yes you are correct, its IP address that uniquely identifies different users who contacts for different purposes. If you would have read the previous answers before reaching here, you would know that IP address is a part of information that socket consists. Think about it, is it possible to have a communication without sockets?. The answer is 'Yes' but you cannot run more than one application in a port but we know that we are not a 'Dump' switch that runs on just hardware.

套接字基本上是网络通信的端点，至少由一个ip地址和一个端口组成。在Java/ c#中，套接字是双向连接一侧的高级实现。

还有Java教程中的一个(非规范的)定义。

一般来说，你会得到很多理论，但区分这两个概念的最简单方法之一是:

为了获得服务，你需要一个服务号码。这个服务号码称为端口。就这么简单。

例如，HTTP as a service运行在端口80上。

现在，许多人都可以请求该服务，并建立了来自客户机-服务器的连接。会有很多联系。每个连接代表一个客户端。为了维护每个连接，服务器为每个连接创建一个套接字来维护其客户端。

An application consists of pair of processes which communicate over the network (client-server pair). These processes send and receive messages, into and from the network through a software interface called socket. Considering the analogy presented in the book "Computer Networking: Top Down Approach". There is a house that wants to communicate with other house. Here, house is analogous to a process, and door to a socket. Sending process assumes that there is a infrastructure on the other side of the door that will transport the data to the destination. Once the message is arrived on the other side, it passes through receiver's door (socket) into the house (process). This illustration from the same book can help you: Sockets are part of transport layer, which provides logical communication to applications. This means that from application's point of view both hosts are directly connected to each other, even though there are numerous routers and/or switches between them. Thus a socket is not a connection itself, it's the end point of the connection. Transport layer protocols are implemented only on hosts, and not on intermediate routers. Ports provide means of internal addressing to a machine. The primary purpose it to allow multiple processes to send and receive data over the network without interfering with other processes (their data). All sockets are provided with a port number. When a segment arrives to a host, the transport layer examines the destination port number of the segment. It then forwards the segment to the corresponding socket. This job of delivering the data in a transport layer segment to the correct socket is called de-multiplexing. The segment's data is then forwarded to the process attached to the socket.