In Computational mechanics, for rate(time) dependent calculations (eg. Creep, plasticity), when we say time step dt, does it mean physical time.

Can I think this way:

I start at time 0 and calculate stress, strain etc  after 1 sec, 2 sec, 3 sec..

Also, what exactly is strain rate? why do some books say ..'when a strain rate is applied'''..I'm confused..dont we just apply displacement or force all the time.

Does it mean that..the expression of strain rate gives how the strain evolves with time...(eg; In creep, under constant load, how the strain evolves with time)

Kindly throw somelight on these..I'm new to computational mechanics..

Harikrishna