Imagine you have a messy list of items.

1. Start at the beginning: Compare each item to the one next to it.
2. Swap if bigger: If an item is bigger than its neighbor, swap their positions in the list.
3. Move on, but leave the biggest behind: After comparing everything, the biggest item will be at the end.
4. Repeat, shrinking the list: Do the same comparisons again, but skip the end (already the biggest). This moves the next biggest item back one step.
5. Keep going until sorted: Continue comparing and swapping, moving towards the front of the list, until all items are in order from smallest to biggest (or biggest to smallest, depending on the sorting goal).

Result of the first pass

This algorithm sorts one data item at a time. One item is taken from the list, and placed in the correct position. This is repeated until there are no more unsorted items in the list. Example below:

Merge sort solves a sorting problem by dividing the list to be sorted into smaller sub-lists, recursively conquering each sub-list by sorting it, and then combining the conquered sub-lists in a specific way to ensure the overall list is sorted.