einschalten
to switch on
To activate and start operating a device, machine, or light using a switch or button.
Vergiss nicht, die Alarmanlage einzuschalten, wenn du gehst.
Don't forget to switch on the alarm system when you leave.

to switch on / involve
Loading your saved state.
to switch on
To activate and start operating a device, machine, or light using a switch or button.
Vergiss nicht, die Alarmanlage einzuschalten, wenn du gehst.
Don't forget to switch on the alarm system when you leave.

'Einschalten' (to switch on / involve) is a separable verb. In a main clause, the prefix 'ein' goes at the end. In subordinate clauses and in the infinitive with 'zu', the verb stays together.
Ich schalte das Licht ein.
I switch on the light.
The three meanings can be distinguished well: If the object is a device, it means 'activate'. If the object is a person or institution, it means 'bring in' or 'involve'. If the verb is reflexive ('sich einschalten'), it means 'to get involved' or 'to interfere'.
Kannst du bitte das Radio einschalten?
Can you please switch on the radio?
In the meaning of 'jemanden hinzuziehen' (to bring someone in), the verb is often combined with people or institutions that help with problems. Typical phrases are: 'die Polizei einschalten' (to involve the police), 'einen Anwalt einschalten' (to involve a lawyer), or 'die Behörden einschalten' (to involve the authorities).
Wegen des Wasserschadens mussten wir einen Experten einschalten.
Because of the water damage, we had to involve an expert.
When someone gets involved in a matter, this is often expressed with the preposition 'in' and the accusative. The structure is: 'sich in etwas (Akk.) einschalten' (to get involved in something).
Der Politiker schaltete sich in die öffentliche Debatte ein.
The politician got involved in the public debate.
to start
'starten' and 'einschalten' can both have to do with devices or technology. 'einschalten' is used when you activate a device, machine, or light with a button or switch. 'starten' is used when an engine, machine, or program is put into operation or begins to run. The words can be confusing because after switching something on, something often starts. In practical terms: you switch on the computer or the light, but you launch a program or start the engine.

Jan schaltet vor dem Termin das Licht im Flur ein.
Jan switches on the light in the hallway before the appointment.
Er hat in der Bibliothek schnell den Laptop gestartet.
He quickly started the laptop in the library.