What is a lock in range and capture range?

Lock-in range: It is the maximum range at which a weapon system with a semi-active seeker (for an example surface to air missile) locks onto a radar source and is able to engage it.

Capture range: The capture range is the maximum distance at which a missile's seeker is able to detect, track, and successfully engage a target on its own without the help of the radar system of the firing platform.