Information Technology Reference
In-Depth Information
was.created.and.by.whom,.when.it.was.edited.and.last.saved,.
the.number.of.characters,.where.it.is.saved.on.the.drive.(its.
address),.and.so.forth..Metadata.are.very.important.to.under-
stand.when.talking.about.electronic.information,.so.we.return.
to.that.later.in.this.topic.
Now,. if. my. computer. shuts. down. unexpectedly. before. I.
have.a.chance.to.save.this.document.to.the.hard.drive,.all.the.
work.I.have.done.will.disappear..That's.because.it.is.stored.in.
volatile.memory.that.goes.away.when.you.either.shut.down.
the.computer.or.close.the.application..As.any.one.of.you.who.
has.had.that.happen.to.you.will.attest,.that.is.a.very.upsetting.
thing..It.has.happened.to.me,.even.while.writing.this.topic,.
and.I.was.not.a.very.happy.person!
We. spend. more. time. talking. about. memory. and. hard.
drives.and.other.types.of.storage.media,.but.it.is.enough.for.
now.to.understand.that.there.is.a.difference.in.how.the.data.
are.kept.in.those.types.of.storage.and.that.if.it.is.volatile.stor-
age,.it.only.lasts.as.long.as.the.application.that.created.it.is.
running..Within.milliseconds.of.closing.down.an.application.
or.turning.off.your.computer,.everything.that.was.stored.in.
memory.fades.away.to.nothing.because.the.power.that.pre-
served.that.memory.was.removed.
So,. there. you. have. it—your. entire. Computer.
Communications.101.course.and.all.in.a.few.easy-to-digest.
pages..Probably.less.than.four.kilobytes.of.digital.information..
With.this.basic.understanding.of.what's.under.the.hood,.you.
are.ready.to.begin.looking.at.the.ways.and.places.that.data.
are.stored.
3.3 DATABASE SYSTEMS
Databases. can. be. hosted. in. many. different. conigurations..
There.are.relatively.simple.databases.created.with.programs.
like.Microsoft.Access.or.FoxPro.and.more.complex.ones.cre-
ated.within.sophisticated.database.applications.such.as.Oracle.
or.MySQL..You.can.even.create.a.database.in.a.spreadsheet.
program.such.as.Microsoft.Excel.
