When looking at security devices and systems for home or business premises we need to look at each device or system, not as individuals but as small cogs in a larger security wheel that need to work together in order to keep the wheel turning.
A good alarm system will act as a good visual deterrent to many criminals however it is always after the break in that the alarm will sound and so here we need to look at the physical locks or barriers to prevent the criminal gaining entry in the first place.
Locks need to be strong enough and of the correct standards to prevent entry using many common techniques, however the lock is only as strong as the door, window, gate, barrier or anything else that it is installed to and so we also need to look at the integrity of doors, frames, walls, glazing, hinges etc.
A good CCTV system is another good visual deterrent and with modern systems these can also be another early warning system working alongside a good alarm system sending a warning to a mobile phone or monitoring station if an intruder crosses a designated line or enters a restricted area, again a CCTV system will not prevent someone gaining entry but it can deter and assist in the conviction of an intruder during or after an event has occurred.
There are many more cogs than the ones mentioned here for assisting the security wheel to turn freely such as electronic access control, door entry systems, security lighting, manned guards, the list goes on however each one needs to be seen as a cog in the same wheel and each needs to be well oiled and working in unison with all the other cogs in order to provide a robust security system that is fit for purpose.