In geometry, any polygon with seven sides and seven angles and seven vertices is called as Heptagon. The sum of angles in a Heptagon is 900°.
Heptagon Picture

In real life, Heptagon shape can be seen in British fifty pence coin which is an equilaterally curved heptagon. The dome in the former Melbourne Magistrates Court in Melbourne, Australia, is a good architectural example for a regular heptagon.
A simple tablet organizer is also a good example for regular Heptagon.
Example of Regular Heptagon

A Heptagon having all sides of equal length and equal angles is called regular Heptagon.

The figure above shows a regular Heptagon. Each of its internal angles is equal to 128.571° (The formula to find an interior angle of an n-sided polygon is given by $\frac{(n-2)\pi}{n}$). In a polygon, the central angle is the angle made at the centre of the polygon by any two adjacent vertices and is given by the formula $\frac{360^o}{n}$. Thus the central angle measure of a regular Heptagon is 51.429°.
The number of distinct diagonals that are possible to draw from all vertices in a polygon is given in general by the formula $\frac{n(n–3)}{2}$. Thus the number of diagonals that can be drawn in a heptagon are 14.

The number of triangles that can be drawn by drawing the diagonals from a given vertex in general is given by n–2 and so we can draw 5 triangles in a regular Heptagon.