- Express.js is a modular web framework for Node.js
- It is used for easier creation of web applications and services
- Express.js simplifies development and makes it easier to write secure, modular and fast applications. You can do all that in plain old Node.js, but some bugs can (and will) surface, including security concerns (eg. not escaping a string properly)
- Redis is an in-memory database system known for its fast
performance. No, but you can use it with Express.js using a redis
client
I couldn't be more concise than this. For all your other needs and information, Google is your friend.