Blocking Adult Content I want to know how can I restrict access to adult content on my android phone  
What. Are the apps available in play store and is there any other permanent way to restrict such content on my phone. So that no one can ever ever get access to this kind of content on my phone.
An easy solution would be changing the DNS server used by your device, by using a DNS server that doesn't resolve porn website hostnames.

You might need a rooted device to change the DNS.

An universal method to change the DNS is by using an app like SetDNS or  OverrideDNS.

Other methods for changing DNS is available here:
(GUIDE) How to Change DNS in Android Device (7 methods)

A few DNS servers that don't resolve porn websites are:


OpenDNS:
208.67.222.123
208.67.220.123
Norton:
199.85.126.20
199.85.127.20


More here:
Source - 5 DNS Services to Block Porn Sites without Installing Software