A URI (Uniform Resource Identifier) is a string used to uniquely identify a resource on the Internet or another network. A URI is used to locate or identify a specific resource, whether it's a web page, a file, an image, a video, or any other type of resource.

A URI can be divided into different parts:

1. URL (Uniform Resource Locator): A specific type of URI used to identify the address of a resource and the mechanism for accessing it. URLs typically include a protocol (such as HTTP or FTP), hostname, port (optional), path, and query string.

2. URN (Uniform Resource Name): A URN is another type of URI used to identify a resource by its name permanently, regardless of its current location or how it is accessed. A well-known example of a URN is the ISBN system for books.

URI is a more general term that encompasses both URLs and URNs. It is an important component of the internet and is used in many applications to access and identify resources.

TLS stands for "Transport Layer Security" and is a protocol designed to secure communication over a computer network, particularly the internet. It serves as the successor to the older Secure Sockets Layer (SSL) protocol and is commonly used for encrypting data to ensure the confidentiality and integrity of transmitted information.

Key functions of TLS include:

1. Encryption: TLS encrypts the data transmission between a client and a server, making it difficult for third parties to understand or manipulate the transmitted information.

2. Authentication: TLS allows for the authentication of communication partners to ensure that the client is connected to the intended server. This is often achieved through the use of digital certificates.

3. Integrity Protection: TLS ensures that transmitted data has not been altered unnoticed during transmission. The application of cryptographic hash functions guarantees the integrity of the data.

4. Support for Various Protocol Versions: TLS exists in different versions (TLS 1.0, TLS 1.1, TLS 1.2, TLS 1.3), with newer versions often bringing improvements in terms of security and performance.

TLS is employed in various applications, including web browsers, email clients, instant messaging applications, and many others, to ensure secure communication over the internet. For instance, when establishing a secure connection to a website (identified by "https://" instead of "http://"), TLS is likely used to encrypt the connection.

FTPS stands for "File Transfer Protocol Secure" and is an enhanced version of the traditional File Transfer Protocol (FTP), incorporating security features through the integration of Transport Layer Security (TLS) or Secure Sockets Layer (SSL). FTPS was developed to address security vulnerabilities associated with FTP, especially when transferring data over insecure networks like the internet.

Key features of FTPS include:

1. Encryption: FTPS encrypts the data transmission between the client and the server to ensure confidentiality. This is achieved through the use of TLS or SSL.

2. Authentication: FTPS provides various authentication methods, including username/password, certificates, and keys, enhancing security during the connection establishment.

3. Port: Similar to FTP, FTPS can operate over ports 21 (clear-text control connection) and 20 (clear-text data connection), or alternative ports for encrypted connections.

4. Modes: FTPS can operate in explicit or implicit modes. In explicit mode, encryption is explicitly requested by the client, while in implicit mode, it is inherent from the start.

FTPS is a popular choice for organizations looking to leverage the benefits of FTP while ensuring that the transmission of sensitive data is secure. It provides a more secure alternative to unencrypted FTP connections and is often deployed in security-critical environments.