<s>
Gravity	O
was	O
a	O
Twitter	O
and	O
social	O
networking	O
client	O
for	O
Symbian	B-Operating_System
smartphones	O
.	O
</s>
<s>
Apart	O
from	O
Twitter	O
it	O
also	O
connected	O
to	O
StatusNet	B-Protocol
,	O
Facebook	B-Application
,	O
Foursquare	B-Application
,	O
Google	B-Application
reader	I-Application
,	O
Sina	B-Protocol
Weibo	I-Protocol
and	O
YouTube	B-General_Concept
.	I-General_Concept
</s>
<s>
In	O
2017	O
an	O
Android	B-Application
based	O
version	O
of	O
Gravity	O
has	O
been	O
released	O
.	O
</s>
