The best defence is to install and keep updated reliable anti-virus software. Both companies offer a range of products suitable for homes and businesses. The protection is usually called a firewall . What we call a spacer is a transparent graphic, just one pixel by one pixel. We use it to precisely control empty space between elements on a web page.
Many web pages use one or more tables as layout control devices.
To create spaces, extra rows, or columns are inserted as needed. The spacer graphic is placed in a cell in an inserted row or column. Cell A Cell B Cell A and Cell B are separated by 15 pixels, exactly . This sets 7 pixels of clear space above and below the graphic. Add a pixel for the graphic itself, and we have 15 pixels of space.