Alkenes and Alkynes

Carbon can from single, double, and triple bonds with Carbon atoms.
The position of the double/triple bonds always has the lowest number and it is in front of the parent chain.

Alkane - single bond
Alkene - double bond
Alkyne - triple bond

Alkenes are hydrocarbons with one or moer double bonds (unsaturated(
They end in -ene from -ane
 E.g  CH3 - CH2- C - CH - CH3                         3ethyl-2pentene
                       |                  -

                    CH2 - CH3

There are also things called Geometric Isomers which are only used in Alkenes. They have the same formula but in different arrangements.

Trans/Cis

*note* This is only used for alkenes.

Trans is used when the CH3 and H3C is on opposite sides (diagonal)
Cis is used when you have CH3 and H3C on the same ( top/top, bottom/bottom)

Alkynes are carbons with 3 or more triple bonds
when naming them you change the ending from -ane and -ene to -yne

Here's a video with more examples