how to select diode

i want to buy the general diode for my project,

how to choose general diode?
what to consider to buy the general diode.

isit only have 1 type of general diode?

The are many considerations depending on use application.

reverse breakdown voltage
current handling
reverse recovery time
junction capacitance
forward voltage drop versus current

Just to name a few.

It all depends on what you want to do with the diode.

If you want a power rectifier, the 1N4007 is a good choice, it will carry 1 amp at up to 1000v. (yes it will work just as well at low voltages!)

If you want a signal diode, the 1N4148 is a good choice.

JimB