Setup the scroll preferences
Often, when browsing a website you have very small pictures on it which are very hard to see. The same is with small text also being really unreadable.
With Mac OS X you can zoom in and out very easily by just holding down Control+Alt and using the scroll wheel of the mouse or your tackpad. There is no need for installing any software.
You may configure other keystrokes and behavior if you open your system preferences. Walk to “keyboard and mouse”, then “mouse”. On the bottom line you will see the current settings.
To enable this feature leave the box checked, otherwise remove the tick.