For exterior use, porcelain is ideal. It is durable, non-porous and frost-resistant, so can be used in outdoor settings such as patios or terraces. There are anti-slip versions available and also formats that are designed to segue from inside to out. In fact a number of Spanish manufacturers have developed special 2cm thick tiles for ease of installation; these can be laid directly on grass or sand, so no substrate is required. Tiles for patios come in various styles, shapes and colours; porcelain can even faithfully replicate stone flags, teak decking or terracotta.
Shown here: Halcon