LeetCode is an online platform founded by Malaysian software engineer Winston Tang in 2015 that allows users to practice and hone their programming skills. The intention is for users to excel in technical interviews in order to land a job at a tech company such as Google, Amazon, Indeed, Microsoft and LinkedIn. It can also be used by people who want to improve their programming skills, people who want to be competitive coders and tech enthusiasts. It offers features that allow uses to use for free and features which a user must pay to access.

FEATURES
LeetCode has the following features.

1.Explore: This section allows users to explore different courses and options.

2.Problems: A series of past technical interviews at some of the companies. This comes in the form of a coding challenge which the user can solve using a programming language of their choice (options include SQL, Java, C#, C++, Python and Go). The user is provided with space to code and has to write code that passes all tests. If the user does so, they are given an idea of how well their solution performed in terms of time and memory. The user is also provided with sections showing all of their submissions, other users' solutions and an editorial by LeetCode which discusses how they will solve it (some of these are free, others are paid). The user is also provided with different study plans which are a collection of the algorithms of a certain type (e.g. Dynamic Programming) which the user may have to pay a subscription fee to access.

3.Contests: This section features programming contests which users may enter to compete against one another.

4.Discussion Forum: This is a discussion forum where users can discuss all issues pertaining to computer science, interviews and careers.

5.Store: A virtual store where user can buy stuff using LeetCode coins.

6.Interview: A section where user can take assessments and practice mock interviews.

Pros
I. Users are challenged to improve their coding skills and to master different algorithms and data structures due to exposure to a variety of challenges of varying difficulties(easy,medium and hard).
II. Exposure to other solutions gives users an idea of the different ways they could improve their solutions or new techniques.
III. Many of the challenges are previous technical interviews at leading companies.
IV. Other users in the community can be helpful and can give feedback.

Cons
I. Challenges, even the easy ones can be very difficult.
II. Challenges are abstract. There aren't any challenges which allow you to build real world applications.

Conclusion
LeetCode is an excellent place to improve your programming skills, build solutions that can pass a variety of tests, practice using different data structures and algorithms and to study with the aim of landing a dream job at a tech company. However, it is not all that there is to Computer Science and Software Engineering. I recommend using this with other resources to become an expert. Please feel free to ask questions or to comment.