Bed bugs are very small insects and feed exclusively on the blood of animals or humans.
Hatched bed bugs are the size of a poppy seed and the adults are ¼ of an inch in length.
They are flat from top to bottom but from above their shape is oval.
Their color can change from almost white after molting to a dark brown.
They don’t develop wings and therefore are unable to fly.
Bed Bug Life Cycle

Bed bugs can hide in very small cracks and crevices and can be carried around in luggage, furniture, pillows, clothing and many such objects when those are moved more or less from homes, apartments and hotels.
They can be picked up visiting a friend that is unaware they have bed bugs, staying at a Hotel/Motel overnight and occasionally on buses, trains or in theaters.
The possibilities are numerous and therefore hard to monitor or control.

We are all vunerable to bed bugs, all walks of life. If you travel frequently, you are more vulnerable due to more frequent hotel, cab, plane usage.
Any place with lots of visitors who sleep or stay for temporary amounts of time is more vunerable than a house that is a permanent residence.
MATTRESS and REST AREAS:
Because they feed mainly at night the first places to look for is around the bed area.
Small drops of blood left behind after they are done feeding.
Dark brown to reddish fecal spots of bed bugs are evident on the bed sheets, mattress or wall closest to the bed.
BITES:

Bites can be found on the arms, legs, back, neck of the host and some people have an allergic reaction ranging from mild to severe swelling of the bite area.

Bed Bugs look similar to other insects so it is important to carefully evaluate with good reference images to confirm their identity.
If still unsure contact the local Pest Control Company which specializes in Bed Bug Remediation.
After their identity has been confirmed it is crucial to devise a plan that will target the bed bugs specifically while limiting unnecessary expense in eradicating them.