So, let's look at an example of equilibrium in the cookie market and see what happens when things change. Let's say the equilibrium price for a chocolate chip cookie is $3. Here's an example of the supply and demand curves, with an equilibrium price of $3, which is at the intersection of the supply and demand curves.
A sigma bond is the end-to-end overlap of the bonding orbitals, usually hybrid orbitals. The sigma bond is a single bond. A pi bond is the side-to-side overlap of unhybridized p-orbitals. A pi bond, along with a sigma bond form a double bond. A triple bond is two pi bonds and a sigma bond. Take a look at this diagram showing a sigma bond and a pi bond, forming a single bond and a double bond. http://metafysica.nl/ethylene01.jpg.
Double and triple covalent bonds are stronger than single covalent bonds and they are characterized by the sharing of four or six electrons between atoms, respectively. Double and triple bonds are comprised of sigma bonds between hybridized orbitals, and pi bonds between unhybridized p orbitals.