.list-inline class in bootstrap is a Inline Unordered List.
If you want to create a horizontal menu using ordered or unordered list you need to place all list items in a single line i.e. side by side. You can do this by simply applying the class
<div class="list-inline">
<a href="#" class="list-inline-item">First item</a>
<a href="#" class="list-inline-item">Secound item</a>
<a href="#" class="list-inline-item">Third item</a>
</div>