Graph is a very broad term, often used interchangeably with "chart". However, they are not the same thing: while all graphs are types of charts, not all charts are graphs. 

Graph vs Chart

GraphChartdata-orientedcategorization-orienteddepict trends and changes in that data over timedepict differences between items

Still - even with the above-mentioned distinction - it is very difficult to properly define such a broad term, and so it might be easier to do that by featuring specific types of graphs. 

There are several ones, from which the most common is e.g.:

• Bar Graph
• Segmented Bar Graph
• Column Graph
• Box and Whiskers Graph (also called a Box Plot)
• Frequency Graph (Frequency Table)
• Cumulative Frequency Table
• Frequency Polygon
• Histogram
• Line Graph
• Timeplot
• Relative Frequency Histogram
• Pie Chart
• Scatter Plot
• Stemplot, etc.