It's great that you want to learn more outside of class. Off the top of my head a good starting place is array, linked list, stack, queue, heap, (un)balanced tree, hash map, priority queue. I would suggest trying to implement each of these yourself if possible a good way to ensure that you understand whats going on. The balanced search tree and hash map are particularly useful to understand. AVL, Red-Black, and 2-3 are different varieties of balanced trees. Priority queue can be implemented with a heap, an augmented tree, or a skip list each implementation has its own pros and cons.

Edit: This GitHub page has a pretty extensive compilation of resources on data structures and algorithms. The guy who made it was a self taught developer who created it to prepare for interviews and ended up landing a job at Amazon.

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If you've been programming in Java you probably already use them. It's just a fancy word for ways to organize elements. Perhaps you've heard of arrays (or lists or dictionaries, depending on the language), or objects. These are data structures. Literal "structures" in which data is stored. Arrays is an organized list of items. Objects are an organized way to encapsulate larger amounts of data with various properties. Obviously this is way oversimplifying, but I think it gets the idea across. More on reddit.com

A "data structure" is a way of organizing information (i.e.: collections of data) Real/Physical world examples: * A list where you add your friend's name and phone number and any other notes one by one as you get them. * A "Contacts" book where you add your friend's names but put them in the appropriate alphabetical section. * A "Rolodex" (or box of index cards) where each person get's their own card. * A grid of columns and rows you draw on graph paper where all names are in the same column, etc. Each of these is a different way to organize or structure the data. AKA: A different data structure. Each has advantages and disadvantages. * Some are easier to get started with (implement). Like the list. * Some are easier to find a name quickly (like the contact book) * Some are easier to add a new person in the middle (like the Rolodex/Index Cards) * Some take up more physical space and are harder to carry around (Like the Rolodex) You choose which to use based on your own criteria. Do you have a small number of people so a little list of 10 is fine? Do you have a large list of people (like 100) where a list would be unwieldly so you buy a little contacts book with alphabetic tabs on the side? Do you add and remove people frequently (like in a business) where a Rolodex is better? Do you need to take the numbers with you (like when you go on vacation) so a little book is better? Or do you only need the numbers when at your desk at work, where a big fat Rolodex is fine?? As far as the built in strings, integers, Booleans, etc.: Programmers generally call those data types, not data structures. Are they technically little data structures? Yeah, maybe. But it's not worth worrying about. Just call those data types and the bigger things data structures. More on reddit.com

Wtf is going on here? http://www.reddit.com/r/learnprogramming/comments/1y5fki/eli5_what_is_an_algorithm/ I'm really curious how this happened. Different accounts, both appear to still be active. Did OP see that question and think that it suited his needs closely enough? But how did he find a 5-month old thread? Are the two accounts the same person? Why not ask an original and unique question? Is OP a robot? More on reddit.com