Bootstrap 3

1. New

1.1. Panels

1.2. Glyphicons

1.3. Jumbotron

1.4. Tiny grid (<768 px)

1.5. Small grid (>768 px)

1.6. Medium grid (>992 px)

1.7. Large grid (>1200 px)

1.8. Offsets

1.9. Push

1.10. Pull

1.11. Input groups

1.12. Form controls

1.13. Button group sizes

1.14. Navbar text

1.15. Navbar header

1.16. Justified tabs / pills

1.17. Responsive images

1.18. Contextual table rows

1.19. Contextual panels

1.20. Modal

1.21. Thumbnail image

1.22. Well sizes

1.23. Alert links

2. Removed

2.1. Form actions

2.2. Search form

2.3. Fluid container

2.4. Fluid row

2.5. Navbar inner

2.6. Dropdown submenu

2.7. Tab alignments

3. Major class changes

3.1. Bootstrap 2.x ==> Bootstrap 3.0

3.2. .container-fluid ==> .container

3.3. .row-fluid ==> .row

3.4. .span* ==> .col-md-*

3.5. .offset* ==> .col-md-offset-*

3.6. .brand ==> .navbar-brand

3.7. .nav-collapse ==> .navbar-collapse

3.8. .nav-toggle ==> .navbar-toggle

3.9. .btn-navbar ==> .navbar-btn

3.10. .hero-unit ==> .jumbotron

3.11. .icon-*==> .glyphicon .glyphicon-*

3.12. .btn ==>.btn .btn-default

3.13. .btn-mini==> .btn-xs

3.14. .btn-small==> .btn-sm

3.15. .btn-large ==>.btn-lg

3.16. .visible-phone==> .visible-sm

3.17. .visible-tablet==> .visible-md

3.18. .visible-desktop==> .visible-lg

3.19. .hidden-phone ==>.hidden-sm

3.20. .hidden-tablet ==>.hidden-md

3.21. .hidden-desktop ==>.hidden-lg

3.22. .input-small ==>.input-sm

3.23. .input-large ==>.input-lg

3.24. .input-prepend .input-append ==> .input-group

3.25. .add-on ==>.input-group-addon

3.26. .thumbnail ==>.img-thumbnail

3.27. ul.unstyled ==>.list-unstyled

3.28. ul.inline ==>.list-inline

4. Browser support

4.1. Chrome (Mac, Windows, iOS, and Android)

4.2. Safari (Mac and iOS only, as Windows has more or less been discontinued)

4.3. Firefox (Mac, Windows)

4.4. Internet Explorer 8+

4.5. Opera (Mac, Windows)