This is the cheat sheet for bootstrap 4 listing many of the classes you need to get a better overview for bootstrap 4. Let me know if you would like to add something or if anything is wrong! Enjoy!
Cheat Sheet
| Class | Description |
| .container | Centered container with fixed width |
| .container-fluid | Full width container |
| .row | Horizontal grouping of columns |
| .col-* | Column with specified width |
| .col | Auto width column |
| .col-sm-* | Column with specified width on small screens |
| .col-md-* | Column with specified width on medium screens |
| .col-lg-* | Column with specified width on large screens |
| .col-xl-* | Column with specified width on extra large screens |
| .col-1 to .col-12 | Columns with specified width |
| .offset-* | Offset a column by specified number of columns |
| .order-* | Change the order of columns |
| .justify-content-* | Align columns horizontally |
| .align-items-* | Align columns vertically |
| .align-self-* | Align a single column vertically |
| .text-* | Align text |
| .bg-* | Background color |
| .text-* | Text color |
| .border-* | Border |
| .rounded-* | Rounded corners |
| .shadow-* | Box shadow |
| .d-* | Display property |
| .flex-* | Flexbox |
| .float-* | Float |
| .position-* | Position |
| .fixed-* | Fixed position |
| .sticky-* | Sticky position |
| .visible-* | Visibility |
| .invisible | Hide element |
| .sr-only | Hide element visually but keep for screen readers |
| .sr-only-focusable | Hide element visually but keep for screen readers and make focusable |
| .show | Show element |
| .hide | Hide element |
| .collapse | Hide element with animation |
| .navbar | Navigation bar |
| .navbar-expand-* | Expand navigation bar on specified screen size |
| .navbar-light | Light navigation bar |
| .navbar-dark | Dark navigation bar |
| .navbar-brand | Brand logo or name |
| .navbar-toggler | Button to toggle navigation bar |
| .navbar-nav | Navigation links |
| .nav-item | Navigation link item |
| .nav-link | Navigation link |
| .dropdown | Dropdown menu |
| .dropdown-toggle | Button to toggle dropdown menu |
| .dropdown-menu | Dropdown menu items |
| .dropdown-item | Dropdown menu item |
| .dropdown-header | Dropdown menu header |
| .dropdown-divider | Divider between dropdown menu items |
| .badge | Badge |
| .badge-* | Badge with specified color |
| .alert | Alert message |
| .alert-* | Alert message with specified color |
| .alert-dismissible | Alert message with close button |
| .close | Close button |
| .modal | Modal dialog |
| .modal-dialog | Modal dialog container |
| .modal-content | Modal dialog content |
| .modal-header | Modal dialog header |
| .modal-body | Modal dialog body |
| .modal-footer | Modal dialog footer |
| .carousel | Image carousel |
| .carousel-item | Image carousel item |
| .carousel-control-prev | Previous image carousel button |
| .carousel-control-next | Next image carousel button |
| .carousel-indicators | Image carousel indicators |
| .list-group | List group |
| .list-group-item | List group item |
| .list-group-item-action | List group item with hover effect |
| .list-group-item-* | List group item with specified color |
| .list-group-flush | Remove borders from list group items |
| .card | Card |
| .card-header | Card header |
| .card-body | Card body |
| .card-footer | Card footer |
| .card-title | Card title |
| .card-subtitle | Card subtitle |
| .card-text | Card text |
| .card-img-top | Card image |
| .card-deck | Deck of cards |
| .card-group | Group of cards |
| .accordion | Accordion |
| .accordion-item | Accordion item |
| .accordion-header | Accordion header |
| .accordion-body | Accordion body |
| .breadcrumb | Breadcrumb |
| .breadcrumb-item | Breadcrumb item |
| .pagination | Pagination |
| .page-item | Pagination item |
| .page-link | Pagination link |
| .badge-pill | Pill shaped badge |
| .rounded-0 | Remove rounded corners |
| .text-center | Center align text |
| .text-left | Left align text |
| .text-right | Right align text |
| .text-justify | Justify text |
| .text-nowrap | Prevent text from wrapping |
| .text-lowercase | Convert text to lowercase |
| .text-uppercase | Convert text to uppercase |
| .text-capitalize | Capitalize first letter of each word |
| .font-weight-bold | Bold text |
| .font-weight-normal | Normal text |
| .font-italic | Italic text |
| .lead | Large font size |
| .display-* | Display property |
| .d-print-* | Display property for printing |
| .d-none | Hide element |
| .d-inline | Inline element |
| .d-inline-block | Inline block element |
| .d-block | Block element |
| .d-table | Table element |
| .d-table-row | Table row element |
| .d-table-cell | Table cell element |
| .flex-row | Flexbox row |
| .flex-column | Flexbox column |
| .flex-wrap | Wrap flexbox items |
| .justify-content-start | Align flexbox items to start |
| .justify-content-end | Align flexbox items to end |
| .justify-content-center | Center align flexbox items |
| .justify-content-between | Space between flexbox items |
| .justify-content-around | Space around flexbox items |
| .align-items-start | Align flexbox items to start |
| .align-items-end | Align flexbox items to end |
| .align-items-center | Center align flexbox items |
| .align-items-baseline | Align flexbox items to baseline |
| .align-items-stretch | Stretch flexbox items |
| .align-content-start | Align flexbox content to start |
| .align-content-end | Align flexbox content to end |
| .align-content-center | Center align flexbox content |
| .align-content-between | Space between flexbox content |
| .align-content-around | Space around flexbox content |
| .align-content-stretch | Stretch flexbox content |
| .align-self-start | Align single flexbox item to start |
| .align-self-end | Align single flexbox item to end |
| .align-self-center | Center align single flexbox item |
| .align-self-baseline | Align single flexbox item to baseline |
| .align-self-stretch | Stretch single flexbox item |
| .float-left | Float element to left |
| .float-right | Float element to right |
| .float-none | Do not float element |
| .position-static | Static position |
| .position-relative | Relative position |
| .position-absolute | Absolute position |
| .position-fixed | Fixed position |
| .position-sticky | Sticky position |
| .fixed-top | Fixed position at top |
| .fixed-bottom | Fixed position at bottom |
| .sticky-top | Sticky position at top |
| .invisible | Hide element |
| .visible | Show element |
| .text-hide | Hide text visually but keep for screen readers |
| .bg-primary | Primary background color |
| .bg-secondary | Secondary background color |
| .bg-success | Success background color |
| .bg-danger | Danger background color |
| .bg-warning | Warning background color |
| .bg-info | Info background color |
| .bg-light | Light background color |
| .bg-dark | Dark background color |
| .bg-white | White background color |
| .text-primary | Primary text color |
| .text-secondary | Secondary text color |
| .text-success | Success text color |
| .text-danger | Danger text color |
| .text-warning | Warning text color |
| .text-info | Info text color |
| .text-light | Light text color |
| .text-dark | Dark text color |
| .text-white | White text color |
| .border | Border |
| .border-top | Top border |
| .border-right | Right border |
| .border-bottom | Bottom border |
| .border-left | Left border |
| .border-0 | Remove border |
| .border-primary | Primary border color |
| .border-secondary | Secondary border color |
| .border-success | Success border color |
| .border-danger | Danger border color |
| .border-warning | Warning border color |
| .border-info | Info border color |
| .border-light | Light border color |
| .border-dark | Dark border color |
| .border-white | White border color |
| .rounded | Rounded corners |
| .rounded-top | Top rounded corners |
| .rounded-right | Right rounded corners |
| .rounded-bottom | Bottom rounded corners |
| .rounded-left | Left rounded corners |
| .rounded-circle | Circle shape |
| .rounded-0 | Remove rounded corners |
| .shadow-sm | Small box shadow |
| .shadow | Medium box shadow |
| .shadow-lg | Large box shadow |
| .shadow-none | Remove box shadow |
Reference:
https://getbootstrap.com/docs/4.0/getting-started/introduction/